TDM transmission for inter-RAT dual connectivity UE

ABSTRACT

Apparatuses, systems, and methods for a wireless device to perform substantially concurrent communications with a next generation network node and a legacy network node. The wireless device may be configured to stablish a first wireless link with a first cell according to a RAT, where the first cell operates in a first system bandwidth and establish a second wireless link with a second cell according to a RAT, where the second cell operates in a second system bandwidth. Further, the wireless device may be configured to perform uplink activity for both the first RAT and the second RAT by TDM uplink data for the first RAT and uplink data for the second RAT if uplink activity is scheduled according to both the first RAT and the second RAT.

PRIORITY DATA

This application claims benefit of priority to U.S. ProvisionalApplication Ser. No. 62/520,375, titled “TDM Transmission for Inter-RATDual Connectivity UE”, filed Jun. 15, 2017, and to U.S. ProvisionalApplication Ser. No. 62/543,417, titled “TDM Transmission for Inter-RATDual Connectivity UE”, filed Aug. 10, 2017, which are herebyincorporated by reference in their entirety as though fully andcompletely set forth herein.

FIELD

The present application relates to wireless devices, and moreparticularly to apparatus, systems, and methods for a wireless device toestablish and maintain concurrent connections with current radio accesstechnologies and next generation radio access technologies.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. Further,wireless communication technology has evolved from voice-onlycommunications to also include the transmission of data, such asInternet and multimedia content. Thus, improvements in the field aredesired.

SUMMARY

Embodiments relate to apparatuses, systems, and methods to performattachment of a wireless device to concurrent (or substantiallyconcurrent) connections with a next generation network node (e.g., afifth generation new radio (5G NR) network node) and a legacy networknode (e.g., an LTE network node).

According to some embodiments, a wireless device may include a firstradio in communication with a first antenna and a second radio incommunication with a second antenna. The first radio may be configuredto perform cellular communication according to a first radio accesstechnology (RAT) and the second radio may be configured to performcellular communication according to a second RAT.

In some embodiments, a wireless device may be configured to performmethods to establish a first wireless link with a first cell accordingto a first radio access technology (RAT), wherein the first celloperates in a first system bandwidth and establish a second wirelesslink with a second cell according to a second radio access technology(RAT), wherein the second cell operates in a second system bandwidth.Further, the wireless device may be configured to determine whether thewireless device has uplink activity scheduled according to both thefirst RAT and the second RAT and perform uplink activity for both thefirst RAT and the second RAT by time division multiplexing (TDM) uplinkdata for the first RAT and uplink data for the second RAT if uplinkactivity is scheduled according to both the first RAT and the secondRAT. In other words, the wireless device may not simultaneously transmiton the first RAT and the second RAT. Said another way, the wirelessdevice may not be configured to transmit on the first RAT and the secondRAT simultaneously. Thus, at least in some embodiments, the wirelessdevice, may not be capable of supporting (and/or performing)simultaneous transmissions on the first RAT and the second RAT. In someembodiments, to perform uplink activity for both the first RAT and thesecond RAT by time division multiplexing (TDM) uplink data for the firstRAT and uplink data for the second RAT if uplink activity is scheduledaccording to both the first RAT and the second RAT, the wireless devicemay be configured to receive an allocation of a first UL subframe fortransmissions according to the first RAT and an allocation of a secondUL subframe for transmissions according to the second RAT. In someembodiments, the TDM of the uplink data may be performed at a physicallayer of the wireless device. In some embodiments, the wireless devicemay be further configured to receive an allocation of a portion of eachUL subframe for control signaling according to one of the first orsecond RATs.

In some embodiments, a wireless device may be configured to performmethods to establish a first wireless link with a first cell accordingto a first radio access technology (RAT), wherein the first celloperates in a first system bandwidth and establish a second wirelesslink with a second cell according to a second radio access technology(RAT), wherein the second cell operates in a second system bandwidth.Further, the wireless device may be configured to determine that thewireless device has uplink activity scheduled according to both thefirst RAT and the second RAT and transmit a message indicating whetherthe wireless device requires a retuning period and/or radio frequency(RF) switching gap (e.g., to switch from a communication frequency ofthe first RAT to a communication frequency of the second RAT). In someembodiments, the retuning period and/or RF switching gap may betransmitted in a capabilities message. In some embodiments, the wirelessdevice may be configured to receive sub-frame allocations for the firstand second RATs based (at least in part) on transmitted indication.

The techniques described herein may be implemented in and/or used with anumber of different types of devices, including but not limited tocellular phones, tablet computers, wearable computing devices, portablemedia players, and any of various other computing devices.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtainedwhen the following detailed description of various embodiments isconsidered in conjunction with the following drawings, in which:

FIG. 1 illustrates an example wireless communication system according tosome embodiments.

FIG. 2 illustrates a base station (BS) in communication with a userequipment (UE) device according to some embodiments.

FIG. 3 illustrates an example block diagram of a UE according to someembodiments.

FIG. 4 illustrates an example block diagram of a BS according to someembodiments.

FIG. 5 illustrates an example block diagram of cellular communicationcircuitry, according to some embodiments.

FIG. 6A illustrates an example of connections between an EPC network, anLTE base station (eNB), and a 5G NR base station (gNB).

FIG. 6B illustrates an example of a protocol stack for an eNB and a gNB.

FIG. 7 illustrates an example of control and user planes, according tosome embodiments.

FIG. 8 illustrates example allocations exchanged between an eNB and agNB over an X₂ interface for TDM for NR NSA operation, according to someembodiments.

FIG. 9 illustrates an example sequence of subframes for TDM for NR NSAoperation, according to some embodiments.

FIG. 10 illustrates an example acknowledgement timeline for TDM for NRNSA operation, according to some embodiments.

FIG. 11 illustrates an example bundled acknowledgement timeline for TDMfor NR NSA operation, according to some embodiments.

FIG. 12 illustrates an example of various LTE TDD configurationsmodified for TDM for NR NSA operation, according to some embodiments.

FIG. 13 illustrates an example sequence of subframes with NR mini-slotfor TDM for NR NSA operation.

FIG. 14 illustrates a block diagram of an example of a method for usingtime division multiplexing (TDM) to support inter-RAT dual connectivity(DC), according to some embodiments.

FIGS. 15A-B illustrate example uplink patterns for NR-LTE dualconnectivity.

FIGS. 16A-B illustrate example uplink patterns for NR-LTE dualconnectivity, according to some embodiments.

FIGS. 17A-B illustrate further example uplink patterns for NR-LTE dualconnectivity, according to some embodiments.

FIG. 18 illustrates a block diagram of an example of a method for usingtime division multiplexing (TDM) to support single carrier,multi-frequency inter-RAT dual connectivity (DC), according to someembodiments.

While the features described herein may be susceptible to variousmodifications and alternative forms, specific embodiments thereof areshown by way of example in the drawings and are herein described indetail. It should be understood, however, that the drawings and detaileddescription thereto are not intended to be limiting to the particularform disclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the subject matter as defined by the appended claims.

DETAILED DESCRIPTION

Terms

The following is a glossary of terms used in this disclosure:

Memory Medium—Any of various types of non-transitory memory devices orstorage devices. The term “memory medium” is intended to include aninstallation medium, e.g., a CD-ROM, floppy disks, or tape device; acomputer system memory or random access memory such as DRAM, DDR RAM,SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,magnetic media, e.g., a hard drive, or optical storage; registers, orother similar types of memory elements, etc. The memory medium mayinclude other types of non-transitory memory as well or combinationsthereof. In addition, the memory medium may be located in a firstcomputer system in which the programs are executed, or may be located ina second different computer system which connects to the first computersystem over a network, such as the Internet. In the latter instance, thesecond computer system may provide program instructions to the firstcomputer for execution. The term “memory medium” may include two or morememory mediums which may reside in different locations, e.g., indifferent computer systems that are connected over a network. The memorymedium may store program instructions (e.g., embodied as computerprograms) that may be executed by one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which performs wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™,iPhone™), laptops, wearable devices (e.g. smart watch, smart glasses),PDAs, portable Internet devices, music players, data storage devices, orother handheld devices, etc. In general, the term “UE” or “UE device”can be broadly defined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is easilytransported by a user and capable of wireless communication.

Base Station—The term “Base Station” has the full breadth of itsordinary meaning, and at least includes a wireless communication stationinstalled at a fixed location and used to communicate as part of awireless telephone system or radio system.

Processing Element—refers to various elements or combinations ofelements that are capable of performing a function in a device, such asa user equipment or a cellular network device. Processing elements mayinclude, for example: processors and associated memory, portions orcircuits of individual processor cores, entire processor cores,processor arrays, circuits such as an ASIC (Application SpecificIntegrated Circuit), programmable hardware elements such as a fieldprogrammable gate array (FPGA), as well any of various combinations ofthe above.

Channel—a medium used to convey information from a sender (transmitter)to a receiver. It should be noted that since characteristics of the term“channel” may differ according to different wireless protocols, the term“channel” as used herein may be considered as being used in a mannerthat is consistent with the standard of the type of device withreference to which the term is used. In some standards, channel widthsmay be variable (e.g., depending on device capability, band conditions,etc.). For example, LTE may support scalable channel bandwidths from 1.4MHz to 20 MHz. In contrast, WLAN channels may be 22 MHz wide whileBluetooth channels may be 1 Mhz wide. Other protocols and standards mayinclude different definitions of channels. Furthermore, some standardsmay define and use multiple types of channels, e.g., different channelsfor uplink or downlink and/or different channels for different uses suchas data, control information, etc.

Band—The term “band” has the full breadth of its ordinary meaning, andat least includes a section of spectrum (e.g., radio frequency spectrum)in which channels are used or set aside for the same purpose.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thus,the term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

Approximately—refers to a value that is almost correct or exact. Forexample, approximately may refer to a value that is within 1 to 10percent of the exact (or desired) value. It should be noted, however,that the actual threshold value (or tolerance) may be applicationdependent. For example, in some embodiments, “approximately” may meanwithin 0.1% of some specified or desired value, while in various otherembodiments, the threshold may be, for example, 2%, 3%, 5%, and soforth, as desired or as required by the particular application.

Concurrent—refers to parallel execution or performance, where tasks,processes, or programs are performed in an at least partiallyoverlapping manner. For example, concurrency may be implemented using“strong” or strict parallelism, where tasks are performed (at leastpartially) in parallel on respective computational elements, or using“weak parallelism”, where the tasks are performed in an interleavedmanner, e.g., by time multiplexing of execution threads.

Various components may be described as “configured to” perform a task ortasks. In such contexts, “configured to” is a broad recitation generallymeaning “having structure that” performs the task or tasks duringoperation. As such, the component can be configured to perform the taskeven when the component is not currently performing that task (e.g., aset of electrical conductors may be configured to electrically connect amodule to another module, even when the two modules are not connected).In some contexts, “configured to” may be a broad recitation of structuregenerally meaning “having circuitry that” performs the task or tasksduring operation. As such, the component can be configured to performthe task even when the component is not currently on. In general, thecircuitry that forms the structure corresponding to “configured to” mayinclude hardware circuits.

Various components may be described as performing a task or tasks, forconvenience in the description. Such descriptions should be interpretedas including the phrase “configured to.” Reciting a component that isconfigured to perform one or more tasks is expressly intended not toinvoke 35 U.S.C. § 112(f) interpretation for that component.

FIGS. 1 and 2—Communication System

FIG. 1 illustrates a simplified example wireless communication system,according to some embodiments. It is noted that the system of FIG. 1 ismerely one example of a possible system, and that features of thisdisclosure may be implemented in any of various systems, as desired.

As shown, the example wireless communication system includes a basestation 102A which communicates over a transmission medium with one ormore user devices 106A, 106B, etc., through 106N. Each of the userdevices may be referred to herein as a “user equipment” (UE). Thus, theuser devices 106 are referred to as UEs or UE devices.

The base station (BS) 102A may be a base transceiver station (BTS) orcell site (a “cellular base station”) and may include hardware thatenables wireless communication with the UEs 106A through 106N.

The communication area (or coverage area) of the base station may bereferred to as a “cell.” The base station 102A and the UEs 106 may beconfigured to communicate over the transmission medium using any ofvarious radio access technologies (RATs), also referred to as wirelesscommunication technologies, or telecommunication standards, such as GSM,UMTS (associated with, for example, WCDMA or TD-SCDMA air interfaces),LTE, LTE-Advanced (LTE-A), 5G new radio (5G NR), HSPA, 3GPP2 CDMA2000(e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), etc. Note that if the base station102A is implemented in the context of LTE, it may alternately bereferred to as an ‘eNodeB’ or ‘eNB’. Note that if the base station 102Ais implemented in the context of 5G NR, it may alternately be referredto as ‘gNodeB’ or ‘gNB’.

As shown, the base station 102A may also be equipped to communicate witha network 100 (e.g., a core network of a cellular service provider, atelecommunication network such as a public switched telephone network(PSTN), and/or the Internet, among various possibilities). Thus, thebase station 102A may facilitate communication between the user devicesand/or between the user devices and the network 100. In particular, thecellular base station 102A may provide UEs 106 with varioustelecommunication capabilities, such as voice, SMS and/or data services.

Base station 102A and other similar base stations (such as base stations102B . . . 102N) operating according to the same or a different cellularcommunication standard may thus be provided as a network of cells, whichmay provide continuous or nearly continuous overlapping service to UEs106A-N and similar devices over a geographic area via one or morecellular communication standards.

Thus, while base station 102A may act as a “serving cell” for UEs 106A-Nas illustrated in FIG. 1, each UE 106 may also be capable of receivingsignals from (and possibly within communication range of) one or moreother cells (which might be provided by base stations 102B-N and/or anyother base stations), which may be referred to as “neighboring cells”.Such cells may also be capable of facilitating communication betweenuser devices and/or between user devices and the network 100. Such cellsmay include “macro” cells, “micro” cells, “pico” cells, and/or cellswhich provide any of various other granularities of service area size.For example, base stations 102A-B illustrated in FIG. 1 might be macrocells, while base station 102N might be a micro cell. Otherconfigurations are also possible.

In some embodiments, base station 102A may be a next generation basestation, e.g., a 5G New Radio (5G NR) base station, or “gNB”. In someembodiments, a gNB may be connected to a legacy evolved packet core(EPC) network and/or to a NR core (NRC) network. In addition, a gNB cellmay include one or more transition and reception points (TRPs). Inaddition, a UE capable of operating according to 5G NR may be connectedto one or more TRPs within one or more gNBs.

Note that a UE 106 may be capable of communicating using multiplewireless communication standards. For example, the UE 106 may beconfigured to communicate using a wireless networking (e.g., Wi-Fi)and/or peer-to-peer wireless communication protocol (e.g., Bluetooth,Wi-Fi peer-to-peer, etc.) in addition to at least one cellularcommunication protocol (e.g., GSM, UMTS (associated with, for example,WCDMA or TD-SCDMA air interfaces), LTE, LTE-A, 5G NR, HSPA, 3GPP2CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), etc.). The UE 106 may alsoor alternatively be configured to communicate using one or more globalnavigational satellite systems (GNSS, e.g., GPS or GLONASS), one or moremobile television broadcasting standards (e.g., ATSC-M/H or DVB-H),and/or any other wireless communication protocol, if desired. Othercombinations of wireless communication standards (including more thantwo wireless communication standards) are also possible.

FIG. 2 illustrates user equipment 106 (e.g., one of the devices 106Athrough 106N) in communication with a base station 102, according tosome embodiments. The UE 106 may be a device with cellular communicationcapability such as a mobile phone, a hand-held device, a computer or atablet, or virtually any type of wireless device.

The UE 106 may include a processor that is configured to execute programinstructions stored in memory. The UE 106 may perform any of the methodembodiments described herein by executing such stored instructions.Alternatively, or in addition, the UE 106 may include a programmablehardware element such as an FPGA (field-programmable gate array) that isconfigured to perform any of the method embodiments described herein, orany portion of any of the method embodiments described herein.

The UE 106 may include one or more antennas for communicating using oneor more wireless communication protocols or technologies. In someembodiments, the UE 106 may be configured to communicate using, forexample, CDMA2000 (1×RTT/1×EV-DO/HRPD/eHRPD) or LTE using a singleshared radio and/or GSM or LTE using the single shared radio. The sharedradio may couple to a single antenna, or may couple to multiple antennas(e.g., for MIMO) for performing wireless communications. In general, aradio may include any combination of a baseband processor, analog RFsignal processing circuitry (e.g., including filters, mixers,oscillators, amplifiers, etc.), or digital processing circuitry (e.g.,for digital modulation as well as other digital processing). Similarly,the radio may implement one or more receive and transmit chains usingthe aforementioned hardware. For example, the UE 106 may share one ormore parts of a receive and/or transmit chain between multiple wirelesscommunication technologies, such as those discussed above.

In some embodiments, the UE 106 may include separate transmit and/orreceive chains (e.g., including separate antennas and other radiocomponents) for each wireless communication protocol with which it isconfigured to communicate. As a further possibility, the UE 106 mayinclude one or more radios which are shared between multiple wirelesscommunication protocols, and one or more radios which are usedexclusively by a single wireless communication protocol. For example,the UE 106 might include a shared radio for communicating using eitherof LTE or 5G NR (or LTE or 1×RTTor LTE or GSM), and separate radios forcommunicating using each of Wi-Fi and Bluetooth. Other configurationsare also possible.

FIG. 3—Block Diagram of a UE

FIG. 3 illustrates an example simplified block diagram of acommunication device 106, according to some embodiments. It is notedthat the block diagram of the communication device of FIG. 3 is only oneexample of a possible communication device. According to embodiments,communication device 106 may be a user equipment (UE) device, a mobiledevice or mobile station, a wireless device or wireless station, adesktop computer or computing device, a mobile computing device (e.g., alaptop, notebook, or portable computing device), a tablet and/or acombination of devices, among other devices. As shown, the communicationdevice 106 may include a set of components 300 configured to performcore functions. For example, this set of components may be implementedas a system on chip (SOC), which may include portions for variouspurposes. Alternatively, this set of components 300 may be implementedas separate components or groups of components for the various purposes.The set of components 300 may be coupled (e.g., communicatively;directly or indirectly) to various other circuits of the communicationdevice 106.

For example, the communication device 106 may include various types ofmemory (e.g., including NAND flash 310), an input/output interface suchas connector I/F 320 (e.g., for connecting to a computer system; dock;charging station; input devices, such as a microphone, camera, keyboard;output devices, such as speakers; etc.), the display 360, which may beintegrated with or external to the communication device 106, andcellular communication circuitry 330 such as for 5G NR, LTE, GSM, etc.,and short to medium range wireless communication circuitry 329 (e.g.,Bluetooth™ and WLAN circuitry). In some embodiments, communicationdevice 106 may include wired communication circuitry (not shown), suchas a network interface card, e.g., for Ethernet.

The cellular communication circuitry 330 may couple (e.g.,communicatively; directly or indirectly) to one or more antennas, suchas antennas 335 and 336 as shown. The short to medium range wirelesscommunication circuitry 329 may also couple (e.g., communicatively;directly or indirectly) to one or more antennas, such as antennas 337and 338 as shown. Alternatively, the short to medium range wirelesscommunication circuitry 329 may couple (e.g., communicatively; directlyor indirectly) to the antennas 335 and 336 in addition to, or insteadof, coupling (e.g., communicatively; directly or indirectly) to theantennas 337 and 338. The short to medium range wireless communicationcircuitry 329 and/or cellular communication circuitry 330 may includemultiple receive chains and/or multiple transmit chains for receivingand/or transmitting multiple spatial streams, such as in amultiple-input multiple output (MIMO) configuration.

In some embodiments, as further described below, cellular communicationcircuitry 330 may include dedicated receive chains (including and/orcoupled to, e.g., communicatively; directly or indirectly. dedicatedprocessors and/or radios) for multiple RATs (e.g., a first receive chainfor LTE and a second receive chain for 5G NR). In addition, in someembodiments, cellular communication circuitry 330 may include a singletransmit chain that may be switched between radios dedicated to specificRATs. For example, a first radio may be dedicated to a first RAT, e.g.,LTE, and may be in communication with a dedicated receive chain and atransmit chain shared with an additional radio, e.g., a second radiothat may be dedicated to a second RAT, e.g., 5G NR, and may be incommunication with a dedicated receive chain and the shared transmitchain.

The communication device 106 may also include and/or be configured foruse with one or more user interface elements. The user interfaceelements may include any of various elements, such as display 360 (whichmay be a touchscreen display), a keyboard (which may be a discretekeyboard or may be implemented as part of a touchscreen display), amouse, a microphone and/or speakers, one or more cameras, one or morebuttons, and/or any of various other elements capable of providinginformation to a user and/or receiving or interpreting user input.

The communication device 106 may further include one or more smart cards345 that include SIM (Subscriber Identity Module) functionality, such asone or more UICC(s) (Universal Integrated Circuit Card(s)) cards 345.

As shown, the SOC 300 may include processor(s) 302, which may executeprogram instructions for the communication device 106 and displaycircuitry 304, which may perform graphics processing and provide displaysignals to the display 360. The processor(s) 302 may also be coupled tomemory management unit (MMU) 340, which may be configured to receiveaddresses from the processor(s) 302 and translate those addresses tolocations in memory (e.g., memory 306, read only memory (ROM) 350, NANDflash memory 310) and/or to other circuits or devices, such as thedisplay circuitry 304, short range wireless communication circuitry 229,cellular communication circuitry 330, connector I/F 320, and/or display360. The MMU 340 may be configured to perform memory protection and pagetable translation or set up. In some embodiments, the MMU 340 may beincluded as a portion of the processor(s) 302.

As noted above, the communication device 106 may be configured tocommunicate using wireless and/or wired communication circuitry. Thecommunication device 106 may be configured to transmit a request toattach to a first network node operating according to the first RAT andtransmit an indication that the wireless device is capable ofmaintaining substantially concurrent connections with the first networknode and a second network node that operates according to the secondRAT. The wireless device may also be configured transmit a request toattach to the second network node. The request may include an indicationthat the wireless device is capable of maintaining substantiallyconcurrent connections with the first and second network nodes. Further,the wireless device may be configured to receive an indication that dualconnectivity with the first and second network nodes has beenestablished.

As described herein, the communication device 106 may include hardwareand software components for implementing the above features for timedivision multiplexing UL data for NSA NR operations. The processor 302of the communication device 106 may be configured to implement part orall of the features described herein, e.g., by executing programinstructions stored on a memory medium (e.g., a non-transitorycomputer-readable memory medium). Alternatively (or in addition),processor 302 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit). Alternatively (or in addition) theprocessor 302 of the communication device 106, in conjunction with oneor more of the other components 300, 304, 306, 310, 320, 329, 330, 340,345, 350, 360 may be configured to implement part or all of the featuresdescribed herein.

In addition, as described herein, processor 302 may include one or moreprocessing elements. Thus, processor 302 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof processor 302. In addition, each integrated circuit may includecircuitry (e.g., first circuitry, second circuitry, etc.) configured toperform the functions of processor(s) 302.

Further, as described herein, cellular communication circuitry 330 andshort range wireless communication circuitry 329 may each include one ormore processing elements. In other words, one or more processingelements may be included in cellular communication circuitry 330 and,similarly, one or more processing elements may be included in shortrange wireless communication circuitry 329. Thus, cellular communicationcircuitry 330 may include one or more integrated circuits (ICs) that areconfigured to perform the functions of cellular communication circuitry330. In addition, each integrated circuit may include circuitry (e.g.,first circuitry, second circuitry, etc.) configured to perform thefunctions of cellular communication circuitry 230. Similarly, the shortrange wireless communication circuitry 329 may include one or more ICsthat are configured to perform the functions of short range wirelesscommunication circuitry 32. In addition, each integrated circuit mayinclude circuitry (e.g., first circuitry, second circuitry, etc.)configured to perform the functions of short range wirelesscommunication circuitry 329.

FIG. 4—Block Diagram of a Base Station

FIG. 4 illustrates an example block diagram of a base station 102,according to some embodiments. It is noted that the base station of FIG.4 is merely one example of a possible base station. As shown, the basestation 102 may include processor(s) 404 which may execute programinstructions for the base station 102. The processor(s) 404 may also becoupled to memory management unit (MMU) 440, which may be configured toreceive addresses from the processor(s) 404 and translate thoseaddresses to locations in memory (e.g., memory 460 and read only memory(ROM) 450) or to other circuits or devices.

The base station 102 may include at least one network port 470. Thenetwork port 470 may be configured to couple to a telephone network andprovide a plurality of devices, such as UE devices 106, access to thetelephone network as described above in FIGS. 1 and 2.

The network port 470 (or an additional network port) may also oralternatively be configured to couple to a cellular network, e.g., acore network of a cellular service provider. The core network mayprovide mobility related services and/or other services to a pluralityof devices, such as UE devices 106. In some cases, the network port 470may couple to a telephone network via the core network, and/or the corenetwork may provide a telephone network (e.g., among other UE devicesserviced by the cellular service provider).

In some embodiments, base station 102 may be a next generation basestation, e.g., a 5G New Radio (5G NR) base station, or “gNB”. In suchembodiments, base station 102 may be connected to a legacy evolvedpacket core (EPC) network and/or to a NR core (NRC) network. Inaddition, base station 102 may be considered a 5G NR cell and mayinclude one or more transition and reception points (TRPs). In addition,a UE capable of operating according to 5G NR may be connected to one ormore TRPs within one or more gNB s.

The base station 102 may include at least one antenna 434, and possiblymultiple antennas. The at least one antenna 434 may be configured tooperate as a wireless transceiver and may be further configured tocommunicate with UE devices 106 via radio 430. The antenna 434communicates with the radio 430 via communication chain 432.Communication chain 432 may be a receive chain, a transmit chain orboth. The radio 430 may be configured to communicate via variouswireless communication standards, including, but not limited to, 5G NR,LTE, LTE-A, GSM, UMTS, CDMA2000, Wi-Fi, etc.

The base station 102 may be configured to communicate wirelessly usingmultiple wireless communication standards. In some instances, the basestation 102 may include multiple radios, which may enable the basestation 102 to communicate according to multiple wireless communicationtechnologies. For example, as one possibility, the base station 102 mayinclude an LTE radio for performing communication according to LTE aswell as a 5G NR radio for performing communication according to 5G NR.In such a case, the base station 102 may be capable of operating as bothan LTE base station and a 5G NR base station. As another possibility,the base station 102 may include a multi-mode radio which is capable ofperforming communications according to any of multiple wirelesscommunication technologies (e.g., 5G NR and Wi-Fi, LTE and Wi-Fi, LTEand UMTS, LTE and CDMA2000, UMTS and GSM, etc.).

As described further subsequently herein, the BS 102 may includehardware and software components for implementing or supportingimplementation of features described herein. The processor 404 of thebase station 102 may be configured to implement or supportimplementation of part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively, theprocessor 404 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit), or a combination thereof. Alternatively(or in addition) the processor 404 of the BS 102, in conjunction withone or more of the other components 430, 432, 434, 440, 450, 460, 470may be configured to implement or support implementation of part or allof the features described herein.

In addition, as described herein, processor(s) 404 may be comprised ofone or more processing elements. In other words, one or more processingelements may be included in processor(s) 404. Thus, processor(s) 404 mayinclude one or more integrated circuits (ICs) that are configured toperform the functions of processor(s) 404. In addition, each integratedcircuit may include circuitry (e.g., first circuitry, second circuitry,etc.) configured to perform the functions of processor(s) 404.

Further, as described herein, radio 430 may be comprised of one or moreprocessing elements. In other words, one or more processing elements maybe included in radio 430. Thus, radio 430 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof radio 430. In addition, each integrated circuit may include circuitry(e.g., first circuitry, second circuitry, etc.) configured to performthe functions of radio 430.

FIG. 5: Block Diagram of Cellular Communication Circuitry

FIG. 5 illustrates an example simplified block diagram of cellularcommunication circuitry, according to some embodiments. It is noted thatthe block diagram of the cellular communication circuitry of FIG. 5 isonly one example of a possible cellular communication circuit. Accordingto embodiments, cellular communication circuitry 330 may be include in acommunication device, such as communication device 106 described above.As noted above, communication device 106 may be a user equipment (UE)device, a mobile device or mobile station, a wireless device or wirelessstation, a desktop computer or computing device, a mobile computingdevice (e.g., a laptop, notebook, or portable computing device), atablet and/or a combination of devices, among other devices.

The cellular communication circuitry 330 may couple (e.g.,communicatively; directly or indirectly) to one or more antennas, suchas antennas 335 a-b and 336 as shown (in FIG. 3). In some embodiments,cellular communication circuitry 330 may include dedicated receivechains (including and/or coupled to, e.g., communicatively; directly orindirectly. dedicated processors and/or radios) for multiple RATs (e.g.,a first receive chain for LTE and a second receive chain for 5G NR). Forexample, as shown in FIG. 5, cellular communication circuitry 330 mayinclude a modem 510 and a modem 520. Modem 510 may be configured forcommunications according to a first RAT, e.g., such as LTE or LTE-A, andmodem 520 may be configured for communications according to a secondRAT, e.g., such as 5G NR.

As shown, modem 510 may include one or more processors 512 and a memory516 in communication with processors 512. Modem 510 may be incommunication with a radio frequency (RF) front end 530. RF front end530 may include circuitry for transmitting and receiving radio signals.For example, RF front end 530 may include receive circuitry (RX) 532 andtransmit circuitry (TX) 534. In some embodiments, receive circuitry 532may be in communication with downlink (DL) front end 550, which mayinclude circuitry for receiving radio signals via antenna 335 a.

Similarly, modem 520 may include one or more processors 522 and a memory526 in communication with processors 522. Modem 520 may be incommunication with an RF front end 540. RF front end 540 may includecircuitry for transmitting and receiving radio signals. For example, RFfront end 540 may include receive circuitry 542 and transmit circuitry544. In some embodiments, receive circuitry 542 may be in communicationwith DL front end 560, which may include circuitry for receiving radiosignals via antenna 335 b.

In some embodiments, a switch 570 may couple transmit circuitry 534 touplink (UL) front end 572. In addition, switch 570 may couple transmitcircuitry 544 to UL front end 572. UL front end 572 may includecircuitry for transmitting radio signals via antenna 336. Thus, whencellular communication circuitry 330 receives instructions to transmitaccording to the first RAT (e.g., as supported via modem 510), switch570 may be switched to a first state that allows modem 510 to transmitsignals according to the first RAT (e.g., via a transmit chain thatincludes transmit circuitry 534 and UL front end 572). Similarly, whencellular communication circuitry 330 receives instructions to transmitaccording to the second RAT (e.g., as supported via modem 520), switch570 may be switched to a second state that allows modem 520 to transmitsignals according to the second RAT (e.g., via a transmit chain thatincludes transmit circuitry 544 and UL front end 572).

In some embodiments, the cellular communication circuitry 330 may beconfigured to establish a first wireless link with a first cellaccording to a first radio access technology (RAT), wherein the firstcell operates in a first system bandwidth and establish a secondwireless link with a second cell according to a second radio accesstechnology (RAT), wherein the second cell operates in a second systembandwidth. Further, the cellular communication circuitry 330 may beconfigured to determine whether the cellular communication circuitry 330has uplink activity scheduled according to both the first RAT and thesecond RAT and perform uplink activity for both the first RAT and thesecond RAT by time division multiplexing (TDM) uplink data for the firstRAT and uplink data for the second RAT if uplink activity is scheduledaccording to both the first RAT and the second RAT. In some embodiments,to perform uplink activity for both the first RAT and the second RAT bytime division multiplexing (TDM) uplink data for the first RAT anduplink data for the second RAT if uplink activity is scheduled accordingto both the first RAT and the second RAT, the cellular communicationcircuitry 330 may be configured to receive an allocation of a first ULsubframe for transmissions according to the first RAT and an allocationof a second UL subframe for transmissions according to the second RAT.In some embodiments, the TDM of the uplink data may be performed at aphysical layer of the cellular communication circuitry 330. In someembodiments, the cellular communication circuitry 330 may be furtherconfigured to receive an allocation of a portion of each UL subframe forcontrol signaling according to one of the first or second RATs.

As described herein, the modem 510 may include hardware and softwarecomponents for implementing the above features or for time divisionmultiplexing UL data for NSA NR operations, as well as the various othertechniques described herein. The processors 512 may be configured toimplement part or all of the features described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively (or inaddition), processor 512 may be configured as a programmable hardwareelement, such as an FPGA (Field Programmable Gate Array), or as an ASIC(Application Specific Integrated Circuit). Alternatively (or inaddition) the processor 512, in conjunction with one or more of theother components 530, 532, 534, 550, 570, 572, 335 and 336 may beconfigured to implement part or all of the features described herein.

In addition, as described herein, processors 512 may include one or moreprocessing elements. Thus, processors 512 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof processors 512. In addition, each integrated circuit may includecircuitry (e.g., first circuitry, second circuitry, etc.) configured toperform the functions of processors 512.

As described herein, the modem 520 may include hardware and softwarecomponents for implementing the above features for time divisionmultiplexing UL data for NSA NR operations, as well as the various othertechniques described herein. The processors 522 may be configured toimplement part or all of the features described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively (or inaddition), processor 522 may be configured as a programmable hardwareelement, such as an FPGA (Field Programmable Gate Array), or as an ASIC(Application Specific Integrated Circuit). Alternatively (or inaddition) the processor 522, in conjunction with one or more of theother components 540, 542, 544, 550, 570, 572, 335 and 336 may beconfigured to implement part or all of the features described herein.

In addition, as described herein, processors 522 may include one or moreprocessing elements. Thus, processors 522 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof processors 522. In addition, each integrated circuit may includecircuitry (e.g., first circuitry, second circuitry, etc.) configured toperform the functions of processors 522.

5G NR Non-Standalone (NSA) Operation with LTE

In some implementations, fifth generation (5G) wireless communicationwill initially be deployed concurrently with current wirelesscommunication standards (e.g., LTE). For example, dual connectivitybetween LTE and 5G new radio (5G NR or NR) has been specified as part ofthe initial deployment of NR. Thus, as illustrated in FIGS. 6A-B,evolved packet core (EPC) network 600 may continue to communicate withcurrent LTE base stations (e.g., eNB 602). In addition, eNB 602 may bein communication with a 5G NR base station (e.g., gNB 604) and may passdata between the EPC network 600 and gNB 604. Thus, EPC network 600 maybe used (or reused) and gNB 604 may serve as extra capacity for UEs,e.g., for providing increased downlink throughput to UEs. In otherwords, LTE may be used for control plane signaling and NR may be usedfor user plane signaling. Thus, LTE may be used to establish connectionsto the network and NR may be used for data services.

FIG. 6B illustrates a proposed protocol stack for eNB 602 and gNB 604.As shown, eNB 602 may include a medium access control (MAC) layer 632that interfaces with radio link control (RLC) layers 622 a-b. RLC layer622 a may also interface with packet data convergence protocol (PDCP)layer 612 a and RLC layer 622 b may interface with PDCP layer 612 b.Similar to dual connectivity as specified in LTE-Advanced Release 12,PDCP layer 612 a may interface via a master cell group (MCG) bearer toEPC network 600 whereas PDCP layer 612 b may interface via a splitbearer with EPC network 600.

Additionally, as shown, gNB 604 may include a MAC layer 634 thatinterfaces with RLC layers 624 a-b. RLC layer 624 a may interface withPDCP layer 622 b of eNB 602 via an X₂ interface for information exchangeand/or coordination (e.g., scheduling of a UE) between eNB 602 and gNB604. In addition, RLC layer 624 b may interface with PDCP layer 614.Similar to dual connectivity as specified in LTE-Advanced Release 12,PDCP layer 614 may interface with EPC network 600 via a secondary cellgroup (SCG) bearer. Thus, eNB 602 may be considered a master node (MeNB)while gNB 604 may be considered a secondary node (SgNB). In somescenarios, a UE may be required to maintain a connection to both an MeNBand a SgNB. In such scenarios, the MeNB may be used to maintain a radioresource control (RRC) connection to an EPC while the SgNB may be usedfor capacity (e.g., additional downlink and/or uplink throughput).

In general, a non-stand alone (NSA) implementation employs dualconnectivity in both uplink (UL) and downlink (DL). In other words, dualconnectivity requires two active radio links in both UL and DL. In someimplementations, depending on frequency band combinations, two(substantially) concurrent UL connections may cause receiver sensitivitydegradation at the UE. For example, in some proposed implementations, aUE may be required to support 4 DL and 1 UL connection in LTE on bands 1(UL: 1920-1980 MHz, DL: 2110-2170 MHz), 3 (UL: 1710-1785 MHz, DL:1805-1880 MHz), 7 (UL: 2500-2570 MHz, DL: 2620-2690 MHz), and 20 (UL:832-862 MHz, DL: 791-821 MHz) while (substantially) concurrentlysupporting 1 DL and 1 UL connection in NR at 3400-3800 MHz. In suchimplementations, a 5^(th) order intermodulation product (IM5) producedat a 5G NR transmitter of the UE from a 2^(nd) harmonic of LTE UL band 3and NR UL may fall into LTE DL band 7 frequencies during (substantially)simultaneous UL operation. Similarly, a 4^(th) order harmonic of LTE ULband 20 and NR UL transmission may create a 5^(th) order intermodulationproduct that may interfere with LTE DL band 7 reception and thusdesensitize a receiving for LTE DL band 7.

In addition, future specifications NR NSA may require a UE to supportco-existence of LTE UL and NR UL within the bandwidth of an LTEcomponent carrier and co-existence of LTE DL and NR DL within thebandwidth of an LTE component carrier. Further, such an implementationmay be further required to minimize impact to NR physical layer designto enable such co-existence and to not impact LTE legacy devices (e.g.,devices that do not support NR) operating on an LTE carrier co-existingwith NR.

Thus, in some implementations of NR NSA, a UE may be configured withmultiple UL carriers on different frequencies (e.g., where there is atleast one LTE carrier and at least one NR carrier of a different carrierfrequency) but operate on either the LTE carrier or the NR carrier at agiven time. In other words, the UE may be configured to operate on onlyone of the carriers at a given time among a pair of LTE and NR carriers.Note that such an implementation may also allow for (substantially)simultaneous operation on two or more UL carriers at a given time.

Embodiments described herein define systems, methods, and mechanisms fora UE to support 5G NSA.

Capability Indication for NR NSA Operation

In some embodiments, a UE, such as communication device 106, may supportLTE and NR co-existence on specific bands and/or frequencies. Inaddition, a UE may determine that for a band combination, UL sharing inNSA mode may be required to avoid receiver sensitivity degradation.Thus, the UE may need to inform the network that UL sharing mode will beused for the LTE/NR band combination. In some embodiments, a conditionalfield may be added to a UE capability message. The conditional field mayindicate whether UL sharing mode will be used for the allocated bandcombination. In addition, the conditional field may indicate whichbands/frequencies that the UE supports NSA operations. Note further thatin some embodiments, e.g., as further described below, the UE may beconfigured to perform NSA operations via time division multiplexing(TDM). However, in other embodiments, the UE may be configured toperform NSA operations via other mechanisms such as frequency divisionmultiplexing (FDM) or MAC layer multiplexing.

TDM Transmission for Inter-RAT Dual Connectivity

In some embodiments, a UE, such as communication device 106, may use asingle UL RF chain for 5G NR and LTE bands, e.g., via cellularcommunication circuitry 330 as illustrated by FIG. 5 above. In someembodiments, the UE may support two downlink RF chains for concurrent(or substantially concurrent) DL operations in 5G NR and LTE, e.g., viacellular communication circuitry 330 as illustrated by FIG. 5 above. Insome embodiments, an LTE cell, such as eNB 602, may not support LTE/NRco-existence on the same carrier, thus, time division multiplexing (TDM)may occur on different frequencies. In some embodiments, an LTE cell,such as eNB 602, may support LTE/NR co-existence on the same carrier,thus TDM may occur on the same frequencies. In some embodiments, TDM forUL transmissions may occur at a physical layer of a protocol stack.

For example, FIG. 7 illustrates an example of an LTE control plane andan NR user plane for TDM for UL transmissions, according to someembodiments. As shown, in some embodiments, a control plane may includea radio resource control (RRC) layer 700, an LTE packet data convergenceprotocol (PDCP) layer 702, an LTE radio link control (RLC) layer 704,and LTE medium access control (MAC) layer 706, and an LTE physicaluplink (Phy UL) layer 708. In addition, a user plane may include anNR-PDCP layer 712, and NR-RLC layer 714, and NR-MAC layer 716, and aNR-Phy UL layer 718. Thus, LTE may be used for control and/or connectionsignaling (e.g., via RRC layer 700) as well as data signaling whereas NRmay be used for data signaling. In some embodiments, the UL datasubframes, e.g., as further described below, may be time divisionmultiplexed (TDM) at the UL physical layer, e.g., as shown by TDM ULtransmit 720. In some embodiments, if an LTE cell (or base station) doesnot support LTE/NR co-existence on a single carrier, the TDM at the ULphysical layer may be on different frequencies. In some embodiments, ifan LTE cell (or base station) does support LTE/NR co-existence on asingle carrier, the TDM at the UL physical layer may be on the samefrequency.

As noted above, an X₂ interface may allow for communication between anLTE base station, e.g. such as eNB 602, and a 5G NR base station, e.g.,such as gNB 604. In particular, in some embodiments, the X₂ may allowfor the LTE-PDCP layer 702 of the control plane to exchangecommunications with the NR-RLC layer 714 of the user plane. In someembodiments, synchronization (e.g., allocation of subframes) between anLTE base station and a NR base station may be enabled via the X₂interface. Note that these allocations, which may be semi-staticresource allocations, may be exchanged to coordinate the eNB and gNB.For example, in LTE, certain UL resources are semi-statically reservedand/or configured, including sounding reference signals (SRS), physicaluplink control channel (PUCCH), and physical random access channel(PRACH), among other channels and resources. In addition, a similarsemi-static allocation approach may be adopted for NR. Thus, to avoidconflicting usage of the semi-statically reserved resources, the eNB andgNB may exchange configurations via the X₂ interface. For example, FIG.8 illustrates example possible subframe allocations negotiated betweenan eNB and a gNB over an X₂ interface for TDM for NR NSA operation,according to some embodiments. As shown, a subframe 811 may include, forexample, one or more frequency bands reserved for LTE physical uplinkcontrol channel (PUCCH) 804 and a frequency band reserved for NR datatransmissions 802. Note that the frequency bands may be reserved for theentire portion of the first subframe 811. As an additional example, asubframe 813 may include one or more frequency bands reserved for LTEPUCCH 804 as well as a frequency band reserved for both NR datatransmissions 802 and LTE sounding reference signal (SRS) 808. Note thata first portion of the subframe may be reserved for NR datatransmissions 802 and a second portion of the subframe may be reservedfor LTE SRS 808 on the frequency band. In other words, the NR datatransmissions 802 and the LTE SRS 808 may be allocated the samefrequency band and scheduled within the same subframe, but at differingtimes within the subframe. As a further example, a subframe 815 mayinclude one or more frequency bands reserved for LTE PUCCH 804 as wellas a frequency band reserved for NR data transmissions 802 and afrequency band reserved for LTE physical random access channel (PRACH)806.

In some embodiments, a semi-static reservation of uplink slots for LTEand NR may simplify a scheduler for both an eNB and a gNB. Thus, timedomain resources for each RAT's UL may be semi-statically configured. Insome embodiments, the configuration may be on a per-UE basis in an RRCre-configuration. For example, for a NSA UE, uplink slots 0, 2, 4, 6, 8may be reserved for LTE uplink and slots 1, 3, 5, 7, 9 may be reservedfor NR uplink. Note that in some embodiments, inter-RAT DC UE's mayshare a (common) configuration. Note further, that in some embodiments,data for a slot/sub-frame may be dynamically scheduled. For example, fora NSA mode UE, in each LTE uplink slot, whether PUSCH is scheduled ornot, which resource blocks are scheduled for LTE PUSCH may bedynamically scheduled by a legacy LTE scheduler.

FIG. 9 illustrates an example semi-static reservation of subframes forTDM for NR NSA operation, according to some embodiments. As shown, oneor more frequency bands may be scheduled (or allocated) for a first UE'sLTE PUCCH 904 in subframes 910, 912, 914, and 916. In addition, afrequency band in subframes 910 and 914 may be scheduled (or allocated)for a second UE's LTE uplink 902. Similarly, a frequency band insubframes 912 and 916 may be scheduled (or allocated) for the secondUE's NR uplink 906. Further, a frequency band may be scheduled (orallocated) for LTE PRACH 908 in subframe 916.

However, separately reserved resources for UL may impact the current LTEdownlink. For example, frequency division duplexing (FDD) assumes anacknowledgement delay of four subframes. Thus, in some embodiments, TDMof uplink subframes may correspond to muting of certain downlinksubframes. For example, based on the semi-static configurationillustrated in FIG. 9, an eNB scheduler and/or a UE may know whichdownlink subframes to skip. For example, FIG. 10 illustrates an exampleLTE acknowledgement timeline for TDM for NR NSA operation, according tosome embodiments. As shown, DL subframe n may be acknowledged (ACK) 4subframes later at UL subframe n+4. Similarly, DL subframe n+1 may beacknowledged at UL subframe n+5. However, since subframe n+6 may bescheduled for NR transmissions, DL subframe n+2 may be skipped or mutedby either of an eNB scheduler, the UE, or both.

Alternatively, in some embodiments, to alleviate potential constraintson LTE DL resources due to LTE DL subframe muting (or skipping), ACKmultiplexing (or ACK bundling) may be used. Note that ACKmultiplexing/bundling is already supported in LTE time divisionduplexing (TDD). Thus, in such embodiments, an eNB may configure a DL/ULpattern for inter-RAT UEs to be similar to (or the same as) as one ofthe LTE TDD frame structures already standardized. For example, FIG. 11illustrates an example bundled acknowledgement LTE timeline for TDM forNR NSA operation, according to some embodiments. As shown, LTE DLsubframe acknowledgments for subframes n−2 through n+1 may be bundled(or multiplexed) and acknowledged at LTE UL subframe n+5. Similarly, LTEDL subframe acknowledgments for subframes n+2 through n+5 may be bundled(or multiplexed) and acknowledged at LTE UL subframe n+9.

As noted above, a UE may acknowledge reception (ACK) or non-reception(NACK) of subframes from a base station a specified number of ULsubframes later. For example, for LTE communications, a subframereceived from an eNB is typically acknowledged (either ACK or NACK) foursubframes after receipt. However, as further noted above, a UE operatingin NR NSA mode may be unable to meet the LTE timeline for ACK/NACK.Thus, in some embodiments, LTE ACK/NACKs and NR ACK/NACKs may bemultiplexed on an NR PUCCH. For example, an NR PUCCH format similar toLTE PUCCH type 3 may be defined and ACK/NACKs from LTE may be taken asfrom other NR carriers. As another example, a field in a NR PUCCH formatmay be reserved for an LTE ACK/NACK payload. In some embodiments, LTEACK/NACKs and NR ACK/NACKs may be multiplexed on an LTE PUCCH. Forexample, ACK/NACK from NR may be taken as from other LTE carriers andmultiplexed with LTE ACK/NACK. In some embodiments, the NR ACK/NACKmultiplexed with the LTE ACK/NACK may be transmitted using one of LTEPUCCH format 3, 4, or 5.

In some embodiments, LTE ACK/NACKs from multiple subframes may bemultiplexed as from different LTE carriers and transmitted using LTEPUCCH format 3, 4, or 5. Note that format selection may be based on anumber (or size) of pending DL ACK/NACKs. In some embodiments, ACK/NACKsfrom multiple subframes may be bundled (e.g., via an AND operationbetween different DL subframes) and transmitted using LTE PUCCH format3, 4, or 5. In some embodiments, the bundling may be a result of a lackof LTE PUCCH resources to multiplex the DL ACK/NACKs from the multiplesubframes. Note that in some embodiments, mapping of ACK/NACK bitsbetween the RATs (e.g., LTE and NR) and subframes may be determined viaRRC signaling between the UE and the eNB/gNB.

In some embodiments, for LTE aperiodic channel state information (CSI)reporting (e.g., reporting of channel quality index (CQI), precodingmatrix indicators (PMI), and rank indicator (RI)) in TDM, an eNB mayonly request aperiodic CSI reports in a DL subframe with an associatedLTE UL subframe. In other words, the eNB may only request an aperiodicCSI report in a DL subframe that corresponds to a subframe in which theUE will be transmitting in LTE (e.g., an LTE subframe). Said anotherway, the eNB may not request an aperiodic CSI report in a DL subframethat corresponds to a subframe in which the UE will be transmitting inNR (e.g., an NR subframe). Alternatively, in some embodiments, if an eNBrequests an aperiodic CSI report in a DL subframe that correspond to anNR subframe, the UE may multiplex the LTE aperiodic CSI report due inthe NR subframe with an NR control payload transmitted in an NR PUCCH orNR PUSCH. As a further alternative, in some embodiments, if an eNBrequests an aperiodic CSI report in a DL subframe that correspond to anNR subframe, the UE may delay the aperiodic CSI report to a subsequentLTE subframe. In some embodiments, a dedicated region for LTE PUCCH maybe reserved in NR PUCCH.

In some embodiments, for LTE periodic CSI reporting in TDM, an eNB mayschedule periodic CSI reporting in LTE subframes and may restrict LTEperiodic CSI reports to integral times of TDM patter periodicity (e.g.,10 milliseconds). For example, for LTE FDD, a configuration with aperiodicity of 10, 20, 40, 80, or 160 milliseconds may be selected.Alternatively, in some embodiments, for LTE periodic CSI reporting inTDM, an eNB may schedule periodic CSI reporting in any subframe and theUE may multiplex LTE periodic CSI reports due in NR subframes with an NRcontrol payload transmitted in an NR PUCCH or NR PUSCH. In someembodiments, a dedicated region for LTE PUCCH may be reserved in NRPUCCH.

In some embodiments, for an LTE scheduling request (SR), an eNB may onlyacknowledge SRs received in LTE subframes and may further restrict SRperiodicity to be integral times of TDM pattern periodicity (e.g., 10milliseconds). For example, for LTE FDD, a configuration with aperiodicity of 10, 20, 40, or 80 milliseconds may be selected.Alternatively, in some embodiments, a UE may transmit an LTE SR ineither LTE or NR subframes. In such embodiments, for NR subframetransmission of an LTE SR, the UE may multiplex the LTE SR with an NRcontrol payload transmitted in an NR PUCCH or NR PUSCH.

As noted, LTE TDD frame structures may be used for scheduling UEssupporting NR NSA operation, in some embodiments. In such embodiments,LTE DL schedules according to LTE TDD frame structures may be used totransmit NR UL. In addition, TDD mechanisms for hybrid automatic repeatrequest (HARD) as well as ACK feedback designed for LTE may be reused.FIG. 12 illustrates an example of various LTE TDD configurationsmodified for TDM for NR NSA operation, according to some embodiments. Asshown, originally scheduled LTE DL transmissions may be scheduled as NRUL transmissions for each of the seven LTE TDD configurations.

In some embodiments, in order to accommodate LTE resources that may besemi-statically reserved, such as SRS in a last symbol of a slot, a miniNR slot may be utilized to allow for the reserved symbols. FIG. 13illustrates an example sequence of subframes with an NR mini-slot forTDM for NR NSA operations, according to some embodiments. As shown,subframe 1311 may include one or more frequency bands 1304 allocated forLTE PUCCH for a UE and a frequency band 1302 allocated for NR ULtransmissions for the UE. Similarly, subframe 1313 may include one ormore frequency bands 1310 allocated for LTE PUCCH for another UE and afrequency band 1306 allocated for LTE UL transmissions for the UE. Inaddition, subframe 1315 may include one or more frequency bands 1304allocated for LTE PUCCH for a UE and a frequency band 1302 allocated forNR UL transmissions for the UE. In addition, subframe 1315 may includean allocation for a frequency band 1308 for SRS that overlaps with thefrequency band allocated for NR UL transmissions, thus the NR ULtransmission allocation may specify a mini NR slot that does not utilizeall of subframe 1315.

In some embodiments, both network and UE may maintain multipleindependent power control loop operating points. For example, for TDM ona common frequency, both RATs (e.g., LTE and NR) may share pathlessestimation (which only depends on frequency) but link adaptation andchannel coding may differ between the RATs, thus power control operatingpoints may differ for the RATs. As another example, for TDM on differentfrequencies, each UL may have different pathloss and different linkadaptation, thus power control operating points may differ for the RATs.

In some embodiments, UL timing advance may be dependent on atransmission frequency band. In other words, since LTE/NR UL may betransmitted on respective bands and different frequencies may havedifferent channel propagation, it may be preferable that each RAT hasindependent timing control. Note that even if LTE/NR UL transmissionsshare the same band, beam forming for each RAT may change packet dataprotocol (PDP) as well. Thus, in some embodiments, if a UE is allocatedresources such that LTE transmissions and NR transmissions are onrespective bands and observed channel properties are not similar (e.g.,PDP), the UE may follow respective timing controls. Alternatively, ifobserved channel properties are similar, LTE timing control may befollowed if a UE is allocated resources such that LTE transmissions andNR transmissions are on an LTE band. On the other hand, if observedchannel properties are similar and a UE is allocated resources such thatLTE transmissions and NR transmissions are on an NR band, LTEtransmissions may use LTE timing control and NR transmissions may followNR timing control.

FIG. 14 illustrates a block diagram of an example of a method for usingtime division multiplexing (TDM) to support inter-RAT dual connectivity(DC), according to some embodiments. The method shown in FIG. 14 may beused in conjunction with any of the systems, techniques, or devicesshown in the above Figures, among other techniques and devices. Invarious embodiments, some of the method elements shown may be performedconcurrently, in a different order than shown, or may be omitted.Additional method elements may also be performed as desired. As shown,this method may operate as follows.

At 1402, a wireless device, such as UE 106, may establish cellular linksaccording to a first RAT and a second RAT. This may include attaching toa first base station that operates according to the first RAT, which mayprovide a first cell operating in a first system bandwidth (e.g.,including a first carrier frequency). This may further include attachingto a second base station that operates according to the second RAT,which may provide a second cell operating in a second system bandwidth(e.g., including a second carrier frequency), which may be differentthan (e.g., non-overlapping with) the first system bandwidth. Note thatthe first base station and the second base station may be differentphysical base stations or may be provided by the same physical basestation and may differ only logically (e.g., a base station may becapable of providing cells according to both the first RAT and thesecond RAT).

In some embodiments, one of the RATs may be LTE and the other RAT may beNR. For example, the first RAT may be NR and the second RAT may be LTE.The order in which the cellular links are established may be arbitraryor may depend on any of various considerations, potentially includingnetwork architecture (e.g., if one of the base stations is intended forNSA operation and/or is a secondary base station), relative signalstrength, relative priority level, etc. As one possibility, the wirelessdevice may initially transmit signaling to an LTE base station, such aseNB 602 described previously herein, to establish an attachment to anLTE network. In other words, the wireless device may request aconnection with the LTE base station.

In some embodiments, prior to transmitting the message, the wirelessdevice may couple (e.g., via a switch) an uplink antenna to a transmitchain dedicated to LTE uplink transmissions, e.g., as described above inreference to FIG. 5. Alternatively, at least according to someembodiments, the wireless device may include sufficient uplink antennasthat LTE and 5G NR uplink activities can be performed concurrently usingseparate antennas.

Continuing with the preceding example, in some instances the wirelessdevice may transmit signaling to a 5G NR base station, such as gNB 604described previously herein, to establish an attachment to a 5G NRnetwork. In other words, the wireless device may request a connectionwith the 5G NR base station. In some embodiments, prior to transmittingthe signaling, the wireless device may couple (e.g., via a switch) anuplink antenna to a transmit chain dedicated to 5G NR uplinktransmissions, e.g., as described above in reference to FIG. 5.Alternatively, as previously noted, the wireless device may includesufficient uplink antennas that LTE and 5G NR uplink activities can beperformed concurrently using separate antennas.

In some instances, the wireless device may receive an indication (e.g.,from the LTE base station) that dual connectivity has been established.In other words, the wireless device may receive a message including oneor more bits indicating that a connection with both the LTE base stationand the 5G NR base station has been established. In some embodiments,the UE may receive the indication via a downlink antenna coupled to areceive chain dedicated to receiving LTE downlink transmissions, e.g.,as described above in reference to FIG. 5.

At 1404, the wireless device may determine whether one or both of thefirst RAT and the second RAT are scheduled to transmit at a given time(e.g., in the same subframe or slot, or otherwise in a temporallyoverlapping manner). The determination may be based on semi-staticand/or dynamic scheduling indications from the first base station and/orthe second base station. For example, in some instances, 5G NR operationmay include time division duplexing between downlink and uplink slots,and indications may be provided of which slots are downlink slots andwhich slots are uplink slots. In LTE operation, certain resources may besemi-statically configured for control signaling. For example, certainresources may be set aside in an LTE uplink carrier for a LTE physicaluplink control channel (PUCCH), a physical random access channel(PRACH), and/or sounding reference signals (SRS), e.g., as describedabove. Additionally, certain resources may be provided (e.g.,dynamically scheduled by providing an uplink grant via downlink controlinformation) for data communication, according to some embodiments.

Thus, as one possibility, the wireless device may receive an uplinkscheduling grant for a first subframe for the first RAT, and may alsoreceive an uplink scheduling grant for the first subframe for the secondRAT, and may determine that the wireless device has uplink activityscheduled according to both the first RAT and the second RAT based onreceiving the uplink scheduling grant for the first subframe for thefirst RAT and receiving the uplink scheduling grant for the firstsubframe for the second RAT. Alternatively, determination whether thewireless device has uplink activity scheduled according to both thefirst RAT and the second RAT may be performed by the network (e.g., by amaster node of a gNB and a eNB, in some instances) and the wirelessdevice may simply be scheduled for uplink activity on only one or theother RAT, or on both RATs, in accordance with uplink allocationsprovided by the network.

If uplink activity is scheduled according to only one or the other RAT,the uplink activity may be performed on the system bandwidth (e.g., onan uplink carrier frequency) associated with that RAT. Thus, thewireless device might perform uplink activity for the first RAT in thefirst system bandwidth if uplink activity is scheduled according to onlythe first RAT and might perform uplink activity for the second RAT inthe second system bandwidth if uplink activity is scheduled according toonly the second RAT.

However, if uplink activity is scheduled according to both first RAT andsecond RAT, at 1406, the wireless device may perform uplink activity forthe first RAT and the second RAT using time division multiplexing (TDM)for data transmissions for the first RAT and the second RAT. In otherwords, the wireless device may not simultaneously transmit on the firstRAT and the second RAT. Said another way, the wireless device may not beconfigured to transmit on the first RAT and the second RATsimultaneously. Thus, at least in some embodiments, the wireless device,may not be capable of supporting (and/or performing) simultaneoustransmissions on the first RAT and the second RAT. In some embodiments,TDM for UL subframes may occur at a UL physical layer of the wirelessdevice. In some embodiments, the TDM may be single carrier (e.g., occuron one of the first or second frequency bands) or multi-carrier.

In some embodiments, a first subframe may be allocated for ULtransmissions according to the first RAT and a second subframe may beallocated for UL transmissions according to the second RAT. In someembodiments, each subframe may include an allocation for controlsignaling according to one of the first or second RAT. In someembodiments, DL subframes for the second RAT corresponding to subframesallocated for UL transmission according to the first RAT may be skipped(or muted) in order to maintain an ACK/NACK timeline of the second RAT.Alternatively, in some embodiments, ACK/NACKs for the second RAT may bemultiplexed and/or bundled. In such embodiments, the bundled/multiplexedACK/NACKs for the second RAT may be transmitted on either a subsequentUL subframe scheduled for the second RAT and/or a subsequent UL subframescheduled for the first RAT (e.g., added to a payload of an ULtransmission according to the first RAT).

Similarly, in some embodiments, the wireless device may receive arequest from one of the base stations for aperiodic and/or periodicchannel state information (CSI). In such embodiments, the wirelessdevice may respond with a CSI report if the request was received in a DLsubframe that corresponds to an UL subframe for which the wirelessdevice is scheduled to transmit to the base station requesting the CSIreport. For example, if the second base station requests the CSI report,then the wireless station may respond with the CSI report if it isreceived in a DL subframe that corresponds to an UL subframe for whichthe wireless device is scheduled to transmit to the second base station.In some embodiments, if the CSI report request is not received in a DLsubframe that has a corresponding UL subframe (e.g., the CSI report isrequested by the second base station but received in a DL subframe thathas a corresponding UL subframe allocated for transmission to the firstbase station), the wireless station may delay transmission of the CSIreport until a subsequent UL subframe that is scheduled for transmissionto the requesting base station. Alternatively, the CSI report may bemultiplexed in any UL subframe on a control payload. For example, if thesecond base station requests the CSI report in a DL subframecorresponding to an UL subframe allocated for transmission to the firstbase station, then the wireless station may multiplex the CSI reportonto a payload of a control channel transmission to the first basestation. In some embodiments, a region in the control channel of thefirst RAT may be reserved for CSI reporting for the second RAT.

In some embodiments, based, at least in part on a first frequency bandallocation associated with the first RAT and a second frequency bandallocation associated with the second RAT, the wireless device maydetermine that the wireless device does not support simultaneous uplinktransmissions using the first and second frequency bands and thewireless device may indicate UL sharing (e.g., using a single frequencyfor transmissions to both the first and second base stations via TDM) tothe first and/or second base station via a conditional field included ina wireless device capability message. In some embodiments, in additionto indicating wireless device UL sharing, the conditional field mayfurther indicate which bands and/or frequencies that the wireless devicesupports NSA operations.

In some embodiments, e.g., as further described below, a wireless deviceusing multiple frequencies to communicate to both the first and secondbase stations, may report a retuning time (e.g., in a capabilitymessage) and/or a radio frequency (RF) switching gap to the first andsecond base stations. The retuning time and/or RF switching gap may bean indication of a time period required by the wireless device to tunefrom a first frequency (e.g., used for uplink communications with thefirst base station) to a second frequency (e.g., used for uplinkcommunications with the second base station). In some embodiments, aretuning time (and/or an RF switching gap) to tune from the firstfrequency to the second frequency may be different than a retuning time(and/or an RF switching gap) to tune from the second frequency to thefirst frequency. In some embodiments, the resolution of the retuningtime (and/or an RF switching gap) may be on the order of symbols ormultiple (e.g., “K”) symbols. In some embodiments, the wireless devicemay provide binary information, e.g., no retuning time (and/or an RFswitching gap) needed (e.g., multiple UL RF chains) or retuning time(and/or an RF switching gap) needed (e.g., shared UL RF chain). In suchembodiments, a network may use a (pre-determined) retuning time/RFswitching gap (e.g., “K” symbols as specified by a standard). In someembodiments, the network may configure a PUCCH format and mini-slotlength for the wireless device to accommodate the retuning time (and/oran RF switching gap) reported by the wireless device. Thus, the networkmay configure (or schedule) transmissions on a per wireless devicebasis. In some embodiments, the wireless device may not report aretuning time (and/or an RF switching gap) and a network may assume(e.g., as specified in a standard) a “worst case” retuning time (and/oran RF switching gap) when configuring UL transmissions for a dualconnectivity wireless device.

FIGS. 15A-B illustrate example uplink patterns for NR-LTE dualconnectivity. The examples shown in FIGS. 15A-B may be applied to NR TDDspectrum, however, similar techniques may also be applied to NR FDDspectrum. In addition, the examples shown in FIGS. 15A-B exemplifyNR-LTE dual connectivity, however, similar techniques may also beapplied to NR-NR dual connectivity or carrier aggregation. In addition,different uplink patterns may also be used.

As illustrated in FIG. 15A, LTE and NR communications may be scheduledusing the same numerology (e.g., 15 kHz subcarrier spacing). In otherwords, LTE and NR communications may be scheduled using the samesubcarrier spacing. LTE uplink communications may occur on a firstfrequency (e.g., LTE UL Frequency 1) and NR communications (uplink anddownlink) may occur on a second frequency (e.g., NR Frequency 3). Asshown, NR downlink communications may coincide (or occur) in the samesub-frames as LTE UL communications (e.g., sub-frames 0, 3, 6, and 9)and NR uplink communications may occur in sub-frames in which LTE ULcommunications are not occurring (e.g., sub-frames 1, 2, 4, 5, 7, and8). Thus, as shown, there is no spacing (e.g., additional NR DLsub-frames) separating LTE UL communications and NR UL communications.

As illustrated in FIG. 15B, LTE and NR communications may be scheduledusing different numerologies (e.g., 15 KHz subcarrier spacing for LTE,30 KHz subcarrier spacing for NR). In other words, LTE and NRcommunications may be scheduled using differing subcarrier spacing,e.g., NR subcarrier spacing may be a multiple of LTE subcarrier spacing.Similar to FIG. 15A, LTE uplink communications may occur on a firstfrequency (e.g., LTE UL Frequency 1) and NR communications (uplink anddownlink) may occur on a second frequency (e.g., NR Frequency 3). Asshown, NR uplink communications may occur in NR sub-frames directlypreceding and/or directly subsequent to LTE UL sub-frames (e.g., LTEsub-frames 0, 3, 6, and 9 and NR sub-frames 2, 5, 8, 11, 14, and 17).Note that the remainder of the NR sub-frames may be used for NR downlinkcommunications. Thus, as shown, there is no spacing (e.g., additional NRDL sub-frames) separating LTE UL communications and NR ULcommunications.

FIGS. 16A-B illustrate example uplink patterns for NR-LTE dualconnectivity, according to some embodiments. The examples shown in FIGS.16A-B may be applied to NR TDD spectrum, however, in some embodiments,similar techniques may also be applied to NR FDD spectrum. In addition,the examples shown in FIGS. 16A-B exemplify NR-LTE dual connectivity,however, in some embodiments, similar techniques may also be applied toNR-NR dual connectivity or NR carrier aggregation. In addition, in someembodiments, different uplink patterns may also be used.

As illustrated in FIG. 16A, LTE and NR communications may be scheduledusing the same numerology (e.g., 15 kHz subcarrier spacing), accordingto some embodiments. In other words, LTE and NR communications may bescheduled using the same subcarrier spacing, in some embodiments. Insome embodiments, LTE uplink communications may occur on a firstfrequency (e.g., LTE UL Frequency 1) and NR communications (uplink anddownlink) may occur on a second frequency (e.g., NR Frequency 3). Asshown, NR downlink communications may coincide (or occur) in the samesub-frames as LTE UL communications (e.g., sub-frames 0, 3, 6, and 9).In some embodiments, the NR uplink subframes may include one or moreguard periods (e.g., guards 1 and 2). In some embodiments, the guardperiods may be based (at least in part) on RF switching gaps (and/orretuning times) reported by a UE and/or specified by a standard based(at least in part) on a UE reporting a requirement for an RF switchinggap (and/or retuning period). Thus, as shown, NR uplink sub-framesdirectly subsequent to LTE uplink sub-frames (e.g., sub-frames 1, 4, and7) may include a guard period at a start of the sub-frame whereas NRuplink sub-frames directly preceding LTE uplink sub-frames (e.g.,sub-frames 2, 5, and 8) may include a guard period at an end of thesub-frame. In other words, guard periods may occur between transitionsfrom LTE uplink to NR uplink and NR uplink to LTE uplink.

As illustrated in FIG. 16B, LTE and NR communications may be scheduledusing different numerologies (e.g., 15 KHz subcarrier spacing for LTE,30 KHz subcarrier spacing for NR), according to some embodiments. Inother words, LTE and NR communications may be scheduled using differingsubcarrier spacing, e.g., NR subcarrier spacing may be a multiple of LTEsubcarrier spacing, in some embodiments. In some embodiments, LTE uplinkcommunications may occur on a first frequency (e.g., LTE UL Frequency 1)and NR communications (uplink and downlink) may occur on a secondfrequency (e.g., NR Frequency 3). As shown, NR uplink communications mayoccur in NR sub-frames directly preceding and/or directly subsequent toLTE UL sub-frames (e.g., LTE sub-frames 0, 3, 6, and 9 and NR sub-frames2, 5, 8, 11, 14, and 17). Note that the remainder of the NR sub-framesmay be used for NR downlink communications. In some embodiments, the NRuplink subframes may include one or more guard periods (e.g., guards 1and 2). In some embodiments, the guard periods may be based (at least inpart) on RF switching gaps (and/or retuning times) reported by a UEand/or specified by a standard based (at least in part) on a UEreporting a requirement for an RF switching gap (and/or retuningperiod). Thus, as shown, NR uplink sub-frames directly subsequent to LTEuplink sub-frames (e.g., sub-frames 3, 9, and 15) may include a guardperiod at a start of the sub-frame whereas NR uplink sub-frames directlypreceding LTE uplink sub-frames (e.g., sub-frames 5, 11, and 17) mayinclude a guard period at an end of the sub-frame. In other words, guardperiods may occur between transitions from LTE uplink to NR uplink andNR uplink to LTE uplink.

FIGS. 17A-B illustrate further example uplink patterns for NR-LTE dualconnectivity, according to some embodiments. The examples shown in FIGS.17A-B may be applied to NR TDD spectrum; however, in some embodiments,similar techniques may also be applied to NR FDD spectrum. In addition,the examples shown in FIGS. 16A-B exemplify NR-LTE dual connectivity;however, in some embodiments, similar techniques may also be applied toNR-NR dual connectivity or NR carrier aggregation. In addition, in someembodiments, different uplink patterns may also be used.

As illustrated in FIG. 17A, LTE and NR communications may be scheduledusing the same numerology (e.g., 15 kHz subcarrier spacing), accordingto some embodiments. In other words, LTE and NR communications may bescheduled using the same subcarrier spacing, in some embodiments. Insome embodiments, LTE uplink communications may occur on a firstfrequency (e.g., LTE UL Frequency 1) and NR communications (uplink anddownlink) may occur on a second frequency (e.g., NR Frequency 3). Asshown, a NR downlink sub-frame may separate LTE uplink and NR uplinkcommunications. In some embodiments, the sub-frame separating the uplinkcommunications may allow for a larger guard period between LTE uplinkand NR uplink communications, e.g., to allow for a larger retuning timefrom/to LTE uplink frequency to/from NR uplink frequency. Note, that ascompared to the example described above in reference to FIG. 16A (e.g.,where the guard period is a portion of an NR sub-frame), the largerretuning time may result in a loss of UL opportunities. In someembodiments, the guard periods may be based (at least in part) on RFswitching gaps (and/or retuning times) reported by a UE and/or specifiedby a standard based (at least in part) on a UE reporting a requirementfor an RF switching gap (and/or retuning period). Thus, as shown, LTEuplink sub-frames may have a NR downlink sub-frame directly subsequentto the LTE uplink sub-frame and directly preceding LTE uplinksub-frames.

As illustrated in FIG. 17B, LTE and NR communications may be scheduledusing different numerologies (e.g., 15 KHz subcarrier spacing for LTE,30 KHz subcarrier spacing for NR), according to some embodiments. Inother words, LTE and NR communications may be scheduled using differingsubcarrier spacing, e.g., NR subcarrier spacing may be a multiple of LTEsubcarrier spacing, in some embodiments. In some embodiments, LTE uplinkcommunications may occur on a first frequency (e.g., LTE UL Frequency 1)and NR communications (uplink and downlink) may occur on a secondfrequency (e.g., NR Frequency 3). As shown, a NR downlink sub-frame mayseparate LTE uplink and NR uplink communications. In some embodiments,the sub-frame separating the uplink communications may allow for alarger guard period between LTE uplink and NR uplink communications,e.g., to allow for a larger retuning time from/to LTE uplink frequencyto/from NR uplink frequency. Note, that as compared to the exampledescribed above in reference to FIG. 16B (e.g., where the guard periodis a portion of an NR sub-frame), the larger retuning time may result ina loss of UL opportunities. In some embodiments, the guard periods maybe based (at least in part) on RF switching gaps (and/or retuning times)reported by a UE and/or specified by a standard based (at least in part)on a UE reporting a requirement for an RF switching gap (and/or retuningperiod). Thus, as shown, LTE uplink sub-frames may have a NR downlinksub-frame directly subsequent to the LTE uplink sub-frame and directlypreceding LTE uplink sub-frames.

FIG. 18 illustrates a block diagram of an example of a method for usingtime division multiplexing (TDM) to support single carriermulti-frequency inter-RAT dual connectivity (DC), according to someembodiments. The method shown in FIG. 18 may be used in conjunction withany of the systems, techniques, or devices shown in the above Figures,among other techniques and devices. In various embodiments, some of themethod elements shown may be performed concurrently, in a differentorder than shown, or may be omitted. Additional method elements may alsobe performed as desired. As shown, this method may operate as follows.

At 1802, a wireless device, such as UE 106, may establish cellular linksaccording to a first RAT and a second RAT. This may include attaching toa first base station that operates according to the first RAT, which mayprovide a first cell operating in a first system bandwidth (e.g.,including a first carrier frequency). This may further include attachingto a second base station that operates according to the second RAT,which may provide a second cell operating in a second system bandwidth(e.g., including a second carrier frequency), which may be differentthan (e.g., non-overlapping with) the first system bandwidth. Note thatthe first base station and the second base station may be differentphysical base stations or may be provided by the same physical basestation and may differ only logically (e.g., a base station may becapable of providing cells according to both the first RAT and thesecond RAT).

In some embodiments, one of the RATs may be LTE and the other RAT may beNR. For example, the first RAT may be NR and the second RAT may be LTE.In some embodiments, both RATs may be NR. The order in which thecellular links are established may be arbitrary or may depend on any ofvarious considerations, potentially including network architecture(e.g., if one of the base stations is intended for NSA operation and/oris a secondary base station), relative signal strength, relativepriority level, etc. As one possibility, the wireless device mayinitially transmit signaling to an LTE base station, such as eNB 602described previously herein, to establish an attachment to an LTEnetwork. In other words, the wireless device may request a connectionwith the LTE base station.

In some embodiments, prior to transmitting the message, the wirelessdevice may couple (e.g., via a switch) an uplink antenna to a transmitchain dedicated to LTE uplink transmissions, e.g., as described above inreference to FIG. 5. Alternatively, at least according to someembodiments, the wireless device may include sufficient uplink antennasthat LTE and 5G NR uplink activities can be performed concurrently usingseparate antennas.

Continuing with the preceding example, in some instances the wirelessdevice may transmit signaling to a 5G NR base station, such as gNB 604described previously herein, to establish an attachment to a 5G NRnetwork. In other words, the wireless device may request a connectionwith the 5G NR base station. In some embodiments, prior to transmittingthe signaling, the wireless device may couple (e.g., via a switch) anuplink antenna to a transmit chain dedicated to 5G NR uplinktransmissions, e.g., as described above in reference to FIG. 5.Alternatively, as previously noted, the wireless device may includesufficient uplink antennas that LTE and 5G NR uplink activities can beperformed concurrently using separate antennas.

In some instances, the wireless device may receive an indication (e.g.,from the LTE base station) that dual connectivity has been established.In other words, the wireless device may receive a message including oneor more bits indicating that a connection with both the LTE base stationand the 5G NR base station has been established. In some embodiments,the UE may receive the indication via a downlink antenna coupled to areceive chain dedicated to receiving LTE downlink transmissions, e.g.,as described above in reference to FIG. 5.

At 1804, the wireless device may determine whether one or both of thefirst RAT and the second RAT are scheduled to transmit at a given time(e.g., in the same subframe or slot, or otherwise in a temporallyoverlapping manner). The determination may be based on semi-staticand/or dynamic scheduling indications from the first base station and/orthe second base station. For example, in some instances, 5G NR operationmay include time division duplexing between downlink and uplink slots,and indications may be provided of which slots are downlink slots andwhich slots are uplink slots. In LTE operation, certain resources may besemi-statically configured for control signaling. For example, certainresources may be set aside in an LTE uplink carrier for a LTE physicaluplink control channel (PUCCH), a physical random access channel(PRACH), and/or sounding reference signals (SRS), e.g., as describedabove. Additionally, certain resources may be provided (e.g.,dynamically scheduled by providing an uplink grant via downlink controlinformation) for data communication, according to some embodiments.

Thus, as one possibility, the wireless device may receive an uplinkscheduling grant for a first subframe for the first RAT, and may alsoreceive an uplink scheduling grant for the first subframe for the secondRAT, and may determine that the wireless device has uplink activityscheduled according to both the first RAT and the second RAT based onreceiving the uplink scheduling grant for the first subframe for thefirst RAT and receiving the uplink scheduling grant for the firstsubframe for the second RAT. Alternatively, determination whether thewireless device has uplink activity scheduled according to both thefirst RAT and the second RAT may be performed by the network (e.g., by amaster node of a gNB and a eNB, in some instances) and the wirelessdevice may simply be scheduled for uplink activity on only one or theother RAT, or on both RATs, in accordance with uplink allocationsprovided by the network.

If uplink activity is scheduled according to only one or the other RAT,the uplink activity may be performed on the system bandwidth (e.g., onan uplink carrier frequency) associated with that RAT. Thus, thewireless device might perform uplink activity for the first RAT in thefirst system bandwidth if uplink activity is scheduled according to onlythe first RAT and might perform uplink activity for the second RAT inthe second system bandwidth if uplink activity is scheduled according toonly the second RAT.

However, if uplink activity is scheduled according to both first RAT andsecond RAT, at 1806, the wireless device may transmit a messageindicating whether the wireless device requires a retuning period and/orRF switching gap, e.g., as described above in reference to FIGS. 16A-Band 17A-B. In some embodiments, the retuning period (or retuning timeand/or RF switching gap) may be reported (or indicated) in a capabilitymessage. In some embodiments, the retuning time and/or RF switching gapmay be an indication of a time period required by the wireless device totune from a first frequency (e.g., used for uplink communications withthe first base station) to a second frequency (e.g., used for uplinkcommunications with the second base station). In some embodiments, aretuning time and/or RF switching gap to tune from the first frequencyto the second frequency may be different than a retuning time and/or RFswitching gap to tune from the second frequency to the first frequency.In some embodiments, the resolution of the retuning time and/or RFswitching gap may be on the order of symbols or multiple (e.g., “K”)symbols. In some embodiments, the wireless device may provide binaryinformation, e.g., no retuning time and/or RF switching gap needed(e.g., multiple UL RF chains) or retuning time and/or RF switching gapneeded (e.g., shared UL RF chain). In such embodiments, a network mayuse a retuning time and/or RF switching gap as specified by a standard(e.g., less than or equal to “K” symbols). In some embodiments, thenetwork may configure a PUCCH format and mini-slot length for thewireless device to accommodate the retuning time and/or RF switching gapreported by the wireless device. Thus, the network may configure (orschedule) transmissions on a per wireless device basis. In someembodiments, the wireless device may not report a retuning time and/orRF switching gap and a network may assume (e.g., as specified in astandard) a “worst case” retuning time when configuring UL transmissionsfor a dual connectivity wireless device.

At 1808, the wireless device may receive sub-frame allocations for thefirst and second RATs based (at least in part) on the indicationtransmitted by the wireless device. In some embodiments, based, at leastin part on a first frequency band allocation associated with the firstRAT and a second frequency band allocation associated with the secondRAT, the wireless device may determine that the wireless device does notsupport uplink transmissions using the first and second frequency bandsand the wireless device may indicate UL sharing (e.g., using a singlefrequency for transmissions to both the first and second base stationsvia TDM) to the first and/or second base station via a conditional fieldincluded in a wireless device capability message. In some embodiments,in addition to indicating wireless device UL sharing, the conditionalfield may further indicate which bands and/or frequencies that thewireless device supports NSA operations.

In some embodiments, the allocation may include one or more guardperiods based, at least in part, on the indication received from thewireless device. In other words, the guard periods may be based (atleast in part) on retuning times and/or RF switching gaps reported bythe wireless device and/or specified by a standard based (at least inpart) on the wireless device reporting a requirement for a retuningperiod and/or RF switching gap. In some embodiments, uplink sub-framesallocated for the first RAT and directly subsequent to uplink sub-framesallocated for the second RAT may include a guard period at a start ofthe sub-frame whereas uplink sub-frames allocated for the first RATdirectly preceding uplink sub-frames allocated for the second RAT mayinclude a guard period at an end of the sub-frame. In other words, guardperiods may occur between transitions from uplink sub-frames allocatedfor the second RAT to uplink sub-frames allocated for the first RAT andbetween transitions from uplink sub-frames allocated for the first RATto uplink sub-frames allocated for the second RAT.

In some embodiments, the one or more guard periods may include downlinksub-frame allocated for the first RAT separating sub-frames allocatedfor the second RAT to uplink sub-frames allocated for the first RAT. Forexample, uplink sub-frames allocated for the second RAT may have adownlink sub-frame allocated for the first RAT directly subsequent tothe uplink sub-frame allocated for the second RAT and directly precedinguplink sub-frames allocated for the second RAT.

In some embodiments, the wireless device may perform uplink activity forthe first RAT and the second RAT using time division multiplexing (TDM)for data transmissions for the first RAT and the second RAT. In otherwords, the wireless device may not simultaneously transmit on the firstRAT and the second RAT. Said another way, the wireless device may not beconfigured to transmit on the first RAT and the second RATsimultaneously. Thus, at least in some embodiments, the wireless device,may not be capable of supporting (and/or performing) simultaneoustransmissions on the first RAT and the second RAT. In some embodiments,TDM for UL subframes may occur at a UL physical layer of the wirelessdevice. In some embodiments, the TDM may be single carrier (e.g., occuron one of the first or second frequency bands) or multi-carrier.

In some embodiments, a first subframe may be allocated for ULtransmissions according to the first RAT and a second subframe may beallocated for UL transmissions according to the second RAT. In someembodiments, each subframe may include an allocation for controlsignaling according to one of the first or second RAT. In someembodiments, DL subframes for the second RAT corresponding to subframesallocated for UL transmission according to the first RAT may be skipped(or muted) in order to maintain an ACK/NACK timeline of the second RAT.Alternatively, in some embodiments, ACK/NACKs for the second RAT may bemultiplexed and/or bundled. In such embodiments, the bundled/multiplexedACK/NACKs for the second RAT may be transmitted on either a subsequentUL subframe scheduled for the second RAT and/or a subsequent UL subframescheduled for the first RAT (e.g., added to a payload of an ULtransmission according to the first RAT).

Similarly, in some embodiments, the wireless device may receive arequest from one of the base stations for aperiodic and/or periodicchannel state information (CSI). In such embodiments, the wirelessdevice may respond with a CSI report if the request was received in a DLsubframe that corresponds to an UL subframe for which the wirelessdevice is scheduled to transmit to the base station requesting the CSIreport. For example, if the second base station requests the CSI report,then the wireless station may respond with the CSI report if it isreceived in a DL subframe that corresponds to an UL subframe for whichthe wireless device is scheduled to transmit to the second base station.In some embodiments, if the CSI report request is not received in a DLsubframe that has a corresponding UL subframe (e.g., the CSI report isrequested by the second base station but received in a DL subframe thathas a corresponding UL subframe allocated for transmission to the firstbase station), the wireless station may delay transmission of the CSIreport until a subsequent UL subframe that is scheduled for transmissionto the requesting base station. Alternatively, the CSI report may bemultiplexed in any UL subframe on a control payload. For example, if thesecond base station requests the CSI report in a DL subframecorresponding to an UL subframe allocated for transmission to the firstbase station, then the wireless station may multiplex the CSI reportonto a payload of a control channel transmission to the first basestation. In some embodiments, a region in the control channel of thefirst RAT may be reserved for CSI reporting for the second RAT.

Further Embodiments

In some embodiments, a wireless device (e.g., such as UE 106) mayperform a method for inter-RAT dual connectivity. In some embodiments,the wireless device, e.g., such as UE 106, may include at least anantenna, a radio coupled to (and/or in communication with) the antenna,and a processing element coupled to (and/or in communication with) theradio. In some embodiments, the method may include program instructionsexecutable by the processing element (and/or processing circuitry) ofthe wireless device. In some embodiments, the method may includeestablishing a first wireless link with a first cell according to afirst radio access technology (RAT), wherein the first cell operates ina first system bandwidth; establishing a second wireless link with asecond cell according to a second radio access technology (RAT), whereinthe second cell operates in a second system bandwidth; determiningwhether the wireless device has uplink activity scheduled according toboth the first RAT and the second RAT; and performing uplink activityfor both the first RAT and the second RAT by time division multiplexing(TDM) uplink data for the first RAT and uplink data for the second RATif uplink activity is scheduled according to both the first RAT and thesecond RAT. In other words, the wireless device may not simultaneouslytransmit on the first RAT and the second RAT. Said another way, thewireless device may not be configured to transmit on the first RAT andthe second RAT simultaneously. Thus, at least in some embodiments, thewireless device, may not be capable of supporting (and/or performing)simultaneous transmissions on the first RAT and the second RAT.

In some embodiments, performing uplink activity for both the first RATand the second RAT by time division multiplexing (TDM) uplink data forthe first RAT and uplink data for the second RAT if uplink activity isscheduled according to both the first RAT and the second RAT may furtherinclude receiving an allocation of a first UL subframe for transmissionsaccording to the first RAT; and receiving an allocation of a second ULsubframe for transmissions according to the second RAT.

In some embodiments, the TDM of the uplink data may be performed at aphysical layer of the wireless device.

In some embodiments, the method may also include the wireless devicereceiving an allocation of a portion of each UL subframe for controlsignaling according to one of the first or second RATs.

In some embodiments, the method may also include the wireless devicereceiving, from the second base station, a request for channel stateinformation in a downlink subframe; determining that the downlinksubframe does not correspond to an UL subframe scheduled fortransmission to the second base station; and multiplexing channel stateinformation regarding the second base station in a control signaltransmitted to the first base station in the UL subframe.

In some embodiments, the method may also include the wireless devicereceiving, from the second base station, an allocation of uplinksubframes, wherein the allocation indicates uplink subframes fortransmission to the first base station and uplink subframes forallocation to the second base station; and receiving, from the secondbase station, an allocation of downlink subframes, wherein theallocation of downlink subframes corresponds to an allocation of uplinksubframes such that the wireless device only receives data from thesecond base station in downlink subframes that correspond to uplinksubframes allocated for transmission to the second base station, therebymaintaining an acknowledgment timeline according to the second RAT.

In some embodiments, the method may also include the wireless devicereceiving, from the second base station, an allocation of uplinksubframes, wherein the allocation indicates uplink subframes fortransmission to the first base station and uplink subframes forallocation to the second base station; receiving, from the second basestation, an allocation of downlink subframes, wherein the allocationindicates the wireless device will receive downlink data in all downlinksubframes; multiplexing acknowledgment of the downlink subframes; andtransmitting the multiplexed acknowledgments in an uplink subframe,thereby maintaining an acknowledgment timeline according to the secondRAT. In some embodiments, the transmitting may occur in an uplinksubframe allocated for transmission to the second base station. In someembodiments, the transmitting may occur in an uplink subframe allocatedfor transmission to the first base station, wherein the multiplexedacknowledgments are included in a payload of a control channeltransmission to the first base station.

In some embodiments, the method may also include the wireless devicereceiving, from the second base station, an allocation of uplinksubframes, wherein the allocation indicates uplink subframes fortransmission to the first base station and uplink subframes forallocation to the second base station; receiving, from the second basestation, an allocation of downlink subframes, wherein the allocationindicates the wireless device will receive downlink data in all downlinksubframes; bundling acknowledgment of the downlink subframes; andtransmitting the bundled acknowledgments in an uplink subframe, therebymaintaining an acknowledgment timeline according to the second RAT. Insome embodiments, the transmitting may occur in an uplink subframeallocated for transmission to the second base station. In someembodiments, the transmitting may occur in an uplink subframe allocatedfor transmission to the first base station, wherein the bundledacknowledgments are included in a payload of a control channeltransmission to the first base station.

In some embodiments, the method may also include the wireless devicereceiving, from one of the first or second base stations, an allocationof a first frequency band associated with the first RAT and a secondfrequency band associated with the second RAT, wherein the first andsecond frequency bands are equivalent.

In some embodiments, the method may also include the wireless devicereceiving, from one of the first or second base stations, an allocationof a first frequency band associated with the first RAT and a secondfrequency band associated with the second RAT, wherein the first andsecond frequency bands are not equivalent.

In some embodiments, the first RAT may comprise 5G NR, and the secondRAT may comprise LTE.

In some embodiments, the method may also include the wireless devicereceiving, from one of the first or second base stations, an allocationof a first frequency band associated with the first RAT and a secondfrequency band associated with the second RAT, wherein the first andsecond frequency bands are equivalent.

In some embodiments, the method may also include the wireless devicereceiving, from one of the first or second base stations, an allocationof a first frequency band associated with the first RAT and a secondfrequency band associated with the second RAT, wherein the first andsecond frequency bands are not equivalent.

In some embodiments, the method may also include the wireless devicereceiving, from one of the first or second base stations, an allocationof a first frequency band associated with the first RAT and a secondfrequency band associated with the second RAT; determining, based inpart on the first and second frequency bands, that the wireless devicedoes not support simultaneous uplink transmissions using the first andsecond frequency bands; and transmitting an indication that the wirelessdevice supports UL sharing for one of the first or second frequencybands to one of the first or second base stations. In some embodiments,the indication may be included in a conditional field of a capabilitymessage. In some embodiments, the conditional field may further includean indication for which bands and/or frequency combinations the wirelessdevice supports UL sharing.

In some embodiments, the method may also include the wireless devicereporting, to the first and/or second base station, an indication of arequired radio frequency (RF) switching gap and/or retuning time,wherein the retuning time and/or switching gap and/or retuning time isassociated with one or more time periods required to switch an RFoperating frequency from a first frequency to a second frequency and/orfrom the second frequency to the first frequency, wherein the firstfrequency is used for transmitting communications to the first basestation, wherein the second frequency is used for transmittingcommunications to the second base station; and receiving, in response tothe reporting, sub-frame allocations for communications with the firstand second base stations, wherein the sub-frame allocations are based,at least in part, on the indication.

In some embodiments, a wireless device (e.g., such as UE 106) mayperform a method for inter-RAT dual connectivity. In some embodiments,the wireless device, e.g., such as UE 106, may include at least anantenna, a radio coupled to (and/or in communication with) the antenna,and a processing element coupled to (and/or in communication with) theradio. In some embodiments, the method may include program instructionsexecutable by the processing element (and/or processing circuitry) ofthe wireless device. In some embodiments, the method may includeestablishing a first wireless link with a first cell according to afirst radio access technology (RAT), wherein the first cell operates ina first system bandwidth; establishing a second wireless link with asecond cell according to a second radio access technology (RAT), whereinthe second cell operates in a second system bandwidth; in response todetermining that the wireless device has uplink activity scheduledaccording to both the first RAT and the second RAT, transmitting anindication of a required radio frequency (RF) switching gap and/orretuning time between different frequencies; and receiving sub-frameallocations for the first cell and the second cell based, at least inpart, on the indication.

In some embodiments, the required retuning time and/or RF switching gapmay be associated with one or more time periods required by the wirelessdevice to switch from a first frequency to a second frequency and/orfrom the second frequency to the first frequency. In some embodiments,the first frequency may be used for transmitting communications to thefirst base station and the second frequency may be used for transmittingcommunications to the second base station. In some embodiments, a firsttime period to switch from the first frequency to the second frequencymay be different than a second time period to switch from the secondfrequency to the first frequency.

In some embodiments, the indication may indicate whether the retuningtime and/or RF switching gap is needed (and/or required). In someembodiments, the indication may indicate that no retuning time and/or RFswitching gap is needed (and/or required).

In some embodiments, the retuning time and/or RF switching gap may bespecified as one of a portion of a downlink sub-frame allocated for thefirst cell and/or at least one downlink sub-frame allocated for thefirst cell. In some embodiments, the retuning time and/or RF switchinggap may be specified via a standard. In some embodiments, the retuningtime and/or RF switching gap may be specified on the order of symbols.In some embodiments, the retuning time and/or RF switching gap may bespecified on the order of multiple symbols.

In some embodiments, the allocations may include a first guard period ata start of sub-frames allocated for transmissions to the first celldirectly subsequent to sub-frames allocated for transmissions to thesecond cell. In some embodiments, the first guard period may beassociated with the required tuning time. In some embodiments, theallocations may include a second guard period at an end of sub-framesallocated for transmissions to the first cell directly precedingsub-frames allocated for transmissions to the second cell. In someembodiments, the second guard period may be associated with the requiredtuning time. In some embodiments, the allocations may include asub-frame allocated for receiving transmissions from the first cellbetween a sub-frame allocated for transmissions to the second cell and asub-frame allocated for transmissions to the first cell. In someembodiments, the allocations may include a sub-frame allocated forreceiving transmissions from the first cell between a sub-frameallocated for transmissions to the first cell and a sub-frame allocatedfor transmissions to the second cell.

In some embodiments, the method may also include the wireless deviceperforming uplink activity for both the first RAT and the second RAT bytime division multiplexing (TDM) uplink data for the first RAT anduplink data for the second RAT if uplink activity is scheduled accordingto both the first RAT and the second RAT. In other words, the wirelessdevice may not simultaneously transmit on the first RAT and the secondRAT. Said another way, the wireless device may not be configured totransmit on the first RAT and the second RAT simultaneously. Thus, atleast in some embodiments, the wireless device, may not be capable ofsupporting (and/or performing) simultaneous transmissions on the firstRAT and the second RAT.

In some embodiments, performing uplink activity for both the first RATand the second RAT by time division multiplexing (TDM) uplink data forthe first RAT and uplink data for the second RAT if uplink activityscheduled according to both the first RAT and the second RAT may includereceiving an allocation of a first UL subframe for transmissionsaccording to the first RAT and receiving an allocation of a second ULsubframe for transmissions according to the second RAT. In someembodiments, the TDM of the uplink data may be performed at a physicallayer of the wireless device.

In some embodiments, the method may further include the wireless devicereceiving an allocation of a portion of each UL subframe for controlsignaling according to one of the first or second RATs.

In some embodiments, the method may further include the wireless devicereceiving, from the second base station, a request for channel stateinformation in a downlink subframe; determining that the downlinksubframe does not correspond to an UL subframe scheduled fortransmission to the second base station; and multiplexing channel stateinformation regarding the second base station in a control signaltransmitted to the first base station in the UL subframe.

In some embodiments, the method may further include the wireless devicereceiving, from the second base station, an allocation of downlinksubframes. In some embodiments, the allocation of downlink subframes maycorrespond to an allocation of uplink subframes such that the wirelessdevice only receives data from the second base station in downlinksubframes that correspond to uplink subframes allocated for transmissionto the second base station, thereby maintaining an acknowledgmenttimeline according to the second RAT.

In some embodiments, the method may further include the wireless devicereceiving, from the second base station, an allocation of downlinksubframes; multiplexing acknowledgment of the downlink subframes; andtransmitting the multiplexed acknowledgments in an uplink subframe,thereby maintaining an acknowledgment timeline according to the secondRAT. In some embodiments, the allocation may indicate the wirelessdevice will receive downlink data in all downlink subframes. In someembodiments, transmitting the multiplexed acknowledgements in an uplinksubframe may occur in an uplink subframe allocated for transmission tothe second base station. In some embodiments, transmitting themultiplexed acknowledgements in an uplink subframe may occur an uplinksubframe allocated for transmission to the first base station, whereinthe multiplexed acknowledgments are included in a payload of a controlchannel transmission to the first base station.

In some embodiments, the method may further include the wireless devicereceiving, from the second base station, an allocation of downlinksubframes; bundling acknowledgment of the downlink subframes; andtransmitting the bundled acknowledgments in an uplink subframe, therebymaintaining an acknowledgment timeline according to the second RAT. Insome embodiments, the allocation may indicate the wireless device willreceive downlink data in all downlink subframes. In some embodiments,transmitting the bundled acknowledgments in an uplink subframe may occurin an uplink subframe allocated for transmission to the second basestation. In some embodiments, transmitting the bundled acknowledgmentsin an uplink subframe may occur in an uplink subframe allocated fortransmission to the first base station, wherein the bundledacknowledgments are included in a payload of a control channeltransmission to the first base station.

In some embodiments, receiving sub-frame allocations for the first celland the second cell based, at least in part, on the indication mayinclude receiving, from one of the first or second base stations, anallocation of a first frequency band associated with the first RAT and asecond frequency band associated with the second RAT. In someembodiments, the first and second frequency bands may not be notequivalent. In some embodiments, such a method may further include thewireless device determining, based in part on the first and secondfrequency bands, that the wireless device does not support uplinktransmissions using the first and second frequency bands andtransmitting an indication for which bands and/or frequency combinationsthat the wireless device supports uplink sharing to one of the first orsecond base stations. In some embodiments, the indication may beincluded in a conditional field of a capability message.

In some embodiments, the first RAT may be 5G NR and the second RAT maybe LTE. In some embodiments, the first RAT may be 5G NR and the secondRAT may be 5G NR.

Embodiments of the present disclosure may be realized in any of variousforms. For example, some embodiments may be realized as acomputer-implemented method, a computer-readable memory medium, or acomputer system. Other embodiments may be realized using one or morecustom-designed hardware devices such as ASICs. Still other embodimentsmay be realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of a methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a UE 106) may be configured toinclude a processor (or a set of processors) and a memory medium, wherethe memory medium stores program instructions, where the processor isconfigured to read and execute the program instructions from the memorymedium, where the program instructions are executable to implement anyof the various method embodiments described herein (or, any combinationof the method embodiments described herein, or, any subset of any of themethod embodiments described herein, or, any combination of suchsubsets). The device may be realized in any of various forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. A user equipment device (UE), comprising: atleast one antenna; at least one radio, wherein the at least one radio isconfigured to perform cellular communication using a first radio accesstechnology (RAT); one or more processors coupled to the at least oneradio, wherein the one or more processors and the at least one radio areconfigured to perform voice and/or data communications; wherein the oneor more processors are configured to cause the UE to: establish a firstwireless link with a first cell according to the first RAT and a secondwireless link with a second cell according to a second RAT, wherein thefirst cell operates in a first system bandwidth, and wherein the secondcell operates in a second system bandwidth; transmit a first indicationthat the UE supports uplink (UL) sharing for one or more of a first orsecond system bandwidths to one of a first or second cells, wherein thefirst and second system bandwidths are at least partially overlapping;provide, to one of the first cell or the second cell, binary informationindicating one of no retuning time needed and retuning time needed; andreceive, from one or more of the first or second cells, an allocation offirst uplink resources associated with the first RAT and an allocationof second uplink resources associated with the second RAT, wherein theallocations correspond to using time division multiplexing (TDM) foruplink data transmissions for the first RAT and the second RAT accordingto the first and second uplink resources.
 2. The UE of claim 1, whereinthe first indication is included in a capability message for a bandcombination.
 3. The UE of claim 1, wherein the one or more processorsare further configured to: report, to one of the first cell or thesecond cell, a second indication of a required switching gap, whereinthe switching gap is associated with one or more time periods requiredto switch from uplink communications with the first cell using the firstRAT to uplink communications with the second cell using the second RATand/or from uplink communications with the second cell using the secondRAT to uplink communications with the first cell using the first RAT. 4.The UE of claim 3, wherein the one or more processors are furtherconfigured to: receive, in response to the reporting, sub-frameallocations for communications with the first cell and the second cell,wherein the sub-frame allocations are based, at least in part, on thesecond indication.
 5. The UE of claim 3, wherein the switching gap isspecified as one of: a portion of a downlink sub-frame allocated for thefirst cell; or at least one downlink sub-frame allocated for the firstcell.
 6. The UE of claim 1, wherein the one or more processors arefurther configured to: receive, from the second cells, an allocation ofuplink subframes, wherein the allocation indicates uplink subframes fortransmission to the first cell and uplink subframes for allocation tothe second cell; receive, from the second cells, an allocation ofdownlink subframes, wherein the allocation indicates the UE will receivedownlink data in all downlink subframes; bundle acknowledgment of thedownlink subframes; and transmit the bundled acknowledgments in anuplink subframe, thereby maintaining an acknowledgment timelineaccording to the second RAT.
 7. The UE of claim 6, wherein the bundledacknowledgments are transmitted in an uplink subframe allocated fortransmission to the second cells.
 8. The UE of claim 6, wherein thebundled acknowledgments are transmitted in an uplink subframe allocatedfor transmission to the first cells, wherein the bundled acknowledgmentsare included in a payload of a control channel transmission to the firstcells.
 9. The UE of claim 1, wherein the first RAT comprises FifthGeneration New Radio (5G NR), and wherein the second RAT comprises LongTerm Evolution (LTE).
 10. An apparatus, comprising: a memory; and atleast one processor in communication with the memory, wherein the atleast one processor is configured to: generate instructions to establisha first wireless link with a first cell according to the first RAT,wherein the first cell operates in a first system bandwidth; generateinstructions to establish a second wireless link with a second cellaccording to a second RAT, wherein the second cell operates in a secondsystem bandwidth; transmit a first indication that the wireless devicesupports uplink sharing for one or more of the first or second frequencysystem bandwidths to one of the first or second cells, wherein the firstand second system bandwidths are at least partially overlapping;provide, to one of the first cell or the second cell, binary informationindicating one of no retuning time needed and retuning time needed;determine whether the wireless device has uplink activity scheduledaccording to both the first RAT and the second RAT; and generateinstructions to perform uplink (UL) activity for both the first RAT andthe second RAT by time division multiplexing (TDM) uplink data for thefirst RAT and uplink data for the second RAT if uplink activity isscheduled according to both the first RAT and the second RAT.
 11. Theapparatus of claim 10, wherein the at least one processor is furtherconfigured to: receive an allocation of a first UL subframe fortransmissions according to the first RAT; and receive an allocation of asecond UL subframe for transmissions according to the second RAT. 12.The apparatus of claim 10, wherein the at least one processor is furtherconfigured to: receive an allocation of a portion of each UL subframefor control signaling according to one of the first or second RATs. 13.The apparatus of claim 10, wherein the at least one processor is furtherconfigured to: receive, from the second cells, a request for channelstate information in a downlink subframe; determine that the downlinksubframe does not correspond to an UL subframe scheduled fortransmission to the second cells; and generate instructions to multiplexchannel state information regarding the second cells in a control signaltransmitted to the first cells in the UL subframe.
 14. The apparatus ofclaim 10, wherein the at least one processor is further configured to:receive, from the second cells, an allocation of uplink subframes,wherein the allocation indicates uplink subframes for transmission tothe first cells and uplink subframes for allocation to the second cells;and receive, from the second cells, an allocation of downlink subframes,wherein the allocation of downlink subframes corresponds to anallocation of uplink subframes such that data from the second cells isonly received in downlink subframes that correspond to uplink subframesallocated for transmission to the second cells, thereby maintaining anacknowledgment timeline according to the second RAT.
 15. Anon-transitory computer readable memory medium storing programinstructions executable by processing circuitry to cause a userequipment device (UE) to: establish a first wireless link with a firstbase station according to a first radio access technology (RAT) and asecond wireless link with a second base station according to a secondRAT, wherein the first base station operates in a first systembandwidth, and wherein the second base station operates in a secondsystem bandwidth; determine that the UE is not configured to transmit onthe first RAT and the second RAT simultaneously; generate instructionsto transmit an indication that the UE is not configured to transmit onthe first RAT and the second RAT simultaneously; provide, to one of thefirst cell or the second cell, binary information indicating one of noretuning time needed and retuning time needed; receive, from one or moreof the first or second cells, an allocation of first uplink resourcesassociated with the first RAT and an allocation of a second uplinkresources associated with the second RAT; and generate instructions toperform uplink (UL) activity for both the first RAT and the second RATaccording to time division multiplexing (TDM) of uplink data for thefirst RAT and uplink data for the second RAT.
 16. The non-transitorycomputer readable memory medium of claim 15, wherein the first andsecond system bandwidths are not overlapping.
 17. The non-transitorycomputer readable memory medium of claim 15, wherein the first andsecond system bandwidths are overlapping.
 18. The non-transitorycomputer readable memory medium of claim 15, wherein the programinstructions are further executable to cause the UE to: report, to oneof the first base station or the second base station, an indication of arequired switching gap, wherein the switching gap is associated with oneor more time periods required to switch from uplink communications withthe first RAT to uplink communications with the second RAT and/or fromuplink communications with the second RAT to uplink communications withthe first RAT.
 19. The non-transitory computer readable memory medium ofclaim 18, wherein the program instructions are further executable tocause the UE to: receive, in response to the reporting, sub-frameallocations for communications with the first base station and thesecond base station, wherein the sub-frame allocations are based, atleast in part, on the indication; wherein the allocations include afirst guard period at a start of sub-frames allocated for transmissionsto the first base station directly subsequent to sub-frames allocatedfor transmissions to the second base station, wherein the first guardperiod is associated with the required radio frequency (RF) switchinggap.
 20. The non-transitory computer readable memory medium of claim 19,wherein a subframe allocation to the UE includes a guard period at anend of sub-frames allocated for transmissions to the first base stationdirectly preceding sub-frames allocated for transmissions to the secondbase station, wherein the second guard period is associated with therequired RF switching gap.